The existential therapist Emmy van Deurzen moved to the UK inspired by RD Laing, the Scottish anti-psychiatrist who said insanity is a “perfectly rational adjustment to an insane world”. It was 1977 and Van Deurzen, who is Dutch and had studied philosophy and psychology in France, found work with the Arbours Association in London, a therapeutic community based on Laing’s ideas, in which people in crisis, psychiatrists and therapists lived together as equals. It was a rude awakening.

Arbours aimed to create space for people to “explore their madness”. “Now that was a very interesting idea,” Van Duerzen says, “but in practice it meant that people self-medicated, with alcohol and pot, and it was not a happy situation.” The residents were often very depressed or psychotic, and it was common to be woken up at night because someone was seeing things or had become suicidal. Van Deurzen came to believe that anti-psychiatry had “lost courage”: it had proposed a different way of thinking about madness, but having released people from asylums and taken them off neuroleptic drugs, it was “kind of leaving them to it”. “And this is what I realised wasn’t good enough,” she says. When people are experiencing a mental health crisis, they need help to make sense of what has happened to them, and to find their way to healing. “From that moment on I just knew: nobody’s doing this. I’m going to have to do it myself,” she says.

With a colleague, she established an existential therapy centre at Arbours, the first of its kind in this country. Existential therapy is “a philosophical approach to therapy and how to live your life in a better way,” Van Deurzen explains, “it is about working with life, rather than just with the psyche”. Although not a household name, Van Deurzen is hugely influential in her field and popularised this form of psychotherapy in the UK. Many of the 350-odd existential therapists accredited by the UK Council for Psychotherapy will have trained at one of the schools she established, and all of them will be familiar with her writing and textbooks.

Van Deurzen became aware of other thinkers who were adopting a similar approach to psychotherapy, including Rollo May and Irvin Yalom in the US. Over the past five decades, existential therapy has grown into a loose, international movement. In 2015, Van Deurzen organised the first ever international congress for existential therapy in London, which was attended by almost 700 people from all over the world.

You could trace the movement’s origins to psychiatrists Ludwig Binswanger and Medard Boss in Switzerland who, in the 1930s, tried to apply Martin Heidegger’s philosophical ideas to understanding mental illness with an existentialist therapy that focused on the patient’s immediate, lived experience rather than just subconscious drives. But Van Deurzen takes a broader view of its intellectual heritage, which she says stretches back to the Athenian philosophers and early Hindu, Buddhist and Taoist thinkers. “Human beings have always had conversations about what’s going wrong in their lives, what it means to be alive, how they can live a better life, how they can become a better person, and how they can make more of this very short time we have to be in this world,” she says.

In her new book, Beginning to Live, the first she has written for a general readership, she draws on the work of many philosophers – not only the canonical existentialists, such as Jean-Paul Sartre, Søren Kierkegaard and Simone de Beauvoir – and demonstrates a knack for distilling complex ideas into something easy to grasp and practical. All over the world, and throughout history, writers have grappled with the same existential questions. “It’s a rich heritage we don’t use enough,” she says.

She is interested in how we can cultivate meaning, courage and freedom despite or because of the suffering life throws at us, a process that begins with how we approach life, how we cultivate our inner worlds. She quotes the psychiatrist and Holocaust survivor Viktor Frankl, who recognised that the one freedom that cannot be taken from us is the freedom “to choose one’s attitude in any given circumstances”, and also the poet Rumi, who wrote: “If you put on shoes that are too tight and walk out across an empty plain, you will not feel the freedom of the place unless you take off your shoes.” Often, Van Deurzen believes, these too-tight shoes are of our own making.

We are speaking over video call. I can see her home office in the background with its dark, tightly packed bookshelves, a glass case of mounted butterflies and a painting of an idyllic woodland path. Van Deurzen is 74 years old and looks as one might imagine a therapist to look – or perhaps a school art teacher or modern-day druid – with a mop of white, candy-floss curls and jewel-coloured clothing. In photographs she sometimes wears a big flower crown. She has barely spoken her native tongue since she left the Netherlands in 1970 and her accent is now hard to place, revealing itself mostly in a slight shifting of vowels so that “come” sounds like its Dutch equivalent, kom.

Her early years, growing up in The Hague, were probably her hardest, she says. To live in postwar Holland was a “very dark, dour experience”. Many people she knew were depressed and still traumatised by the Nazi occupation. Money was tight. Her parents had endured the famine of 1944-45. Her father, an antiques expert, had joined the resistance and almost died after spending a winter hiding in an unheated loft and catching pneumonia. At night, she heard her neighbour screaming as he relived his torture in a Japanese prisoner of war camp.

“I struggled with wanting to be a part of life, really, looking at how terrible it all was,” she recalls. At 15, Van Deurzen fell wildly in love with a 20-year-old Frenchman she met on a camping holiday in Portugal. For two years he wrote letters to her daily, and they met when they could. Then he ghosted her. She was devastated and spiralled into depression. She tried to kill herself twice. After the second attempt, she told her father, who took her to the school rector. The rector enlisted her help to find out why so many students were struggling emotionally: two pupils had died in the previous year – one in a traffic accident while on LSD, and another as a result of suicide. Van Deurzen found a renewed sense of purpose, and ultimately a vocation. “It is the event that seems like a catastrophe that saves you,” she writes in her book.

At 18, she left for the University of Montpellier Paul Valéry, where she studied philosophy and began training as a psychoanalyst. There she met her first husband, Jean-Pierre, a young psychiatrist, whom she married in 1972. The couple found work at St Alban, a pioneering psychiatric hospital, and later moved to other French hospitals that were experimenting with innovative, less coercive forms of mental health care. Van Deurzen worked as a psychoanalyst and began to develop her “philosophical method” of talking with patients.

She started structuring each conversation like a Socratic dialogue, asking open-ended questions and challenging a person’s assumptions. “Instead of standing in judgment or making decisions about what was wrong with the person, I was allowing this philosophical exploration to take place,” she says. Van Deurzen also studied for a master’s in clinical psychology.

Soon after she moved to the UK, she and Jean-Pierre split up. Van Deurzen opened her first private practice in 1978. She says that being a woman in a male-dominated field was “part of my struggle and part of my privilege”. “I was going to do things my way, because I felt it was about time to have a more female approach, and felt quite free to come up with my own. Because, really, there weren’t very many female existential philosophers,” she says. De Beauvoir, Hannah Arendt and Lou Andreas-Salomé are inspirations.

Nowadays Van Deurzen heads up Dilemma Consultancy, which offers low-cost existential therapy in London, as well as two training centres: the Existential Academy and the New School of Psychotherapy and Counselling, with her third husband, the psychiatrist Digby Tantam. She still treats people with psychosis (as part of a wider care team), but most of her clients are experiencing other forms of distress or feel stuck in life. She says she has come to believe that depression “is really a form of oppression”.

“From the moment I started working in the field, I started getting the feeling that when I sat with a depressed person it always felt like, you know, they bend over, it’s like there is a burden on them, it is like there is no room for them and they haven’t got the energy to make room either. And I started to think: they’re oppressed. And then I began to realise that there are many different ways for people to be oppressed, and sometimes we oppress ourselves,” she says.

Therapy often seems a mysterious process: how and why should it help people feel better? Van Deurzen says when she talks to people, she tries to meet them at their greatest point of pain, because “where it hurts, they want relief, even if they have given up”. She asks about what is hurting, and the ways in which they feel they have been thwarted. “Because the pain is usually the result of feeling that the world has knocked you down or has stopped you in your tracks or has not recognised you, or has excluded you from the family or from another group. So there’s a very concrete and real pain about where they are in the world. And that situation can be discussed, it can be opened up to their understanding, where they are no longer a victim of it,” she says.

Anti-psychiatrists are often very critical of antidepressants and other mental health drugs, but Van Deurzen says that it is not her place to tell people what medication they should or shouldn’t take. She says it is easier to undergo existential therapy “if you’re not too drugged”, because some medications – especially those used to treat psychosis – affect a person’s cognition. But she also understands why people seek medical relief from their suffering. “We know that many people who have been depressed have felt that they were helped by taking antidepressants. And just the fact they could take something that would change their mental state, which it does do, was helpful to them, because it gave them some pause, some time to start thinking about things in a different way,” she says.

In her book, Van Deurzen writes about helping people rediscover their existential courage in the face of life’s struggles and uncertainty. Has she found existential courage? “Oh, very much so! Yes, goodness me. It’s been a long journey for me. I’m an old lady!” she says. She describes the feeling as a “lightening of the heart”. “I experience it more as: oh yes, I can see what is happening. We can do this. We can rise to this. We can make ourselves lighter,” she says.

A few days after our interview, I have therapy with Van Deurzen. She had offered me a few sessions so that I could better understand what existential therapy is, and because of tight deadlines we arranged one double session that would be 100 minutes long. I was very curious – the existential approach appealed to me, as a former philosophy undergraduate – and nervous, having never had therapy before. What followed was entirely unexpected and is hard to write about – not only because it was intensely personal, but because a reader might expect a journalist to maintain a healthy degree of scepticism and distance from their subject, and I lost that distance.

It sounds too corny – too convenient – to be true, but my conversation with Van Deurzen was one of the most profound and potentially life-altering encounters I’ve had. I am not depressed, in fact I am happier and more fulfilled than I have ever been, but I have lived most of my life expecting catastrophe around every corner, and I had assumed this was an unsolvable problem – how is anyone to hold their nerve when they know that nothing good can ever last? Van Deurzen did not mention philosophy in our session, but she had a warm, inquiring manner and she challenged me, invited me to view some of the defining events in my life in a different light. At the end, I was exhausted and had cried so much I could barely see, but I also felt less fearful, more optimistic. This optimism has persisted. I can see a new way out of my mental doom loops; it seems possible I may, with time and effort, learn a different relationship to risk and uncertainty. I relistened to my interview the day after therapy and when Van Deurzen describes courage as “a lightening of the heart” I thought: “That’s it! That’s how this feels!”

Will existential therapy change my life? Maybe. As a millennial, I grew up at a time when many people believed therapy was only for people with serious issues. Thankfully, the stigma surrounding mental illness is lifting and most people see the value of psychological exploration. Schools place much greater emphasis on fostering emotional awareness and intelligence: “That is real progress in the world,” Van Deurzen says, though she would like things to move further. “If [children] end up feeling ‘oh, I’m sad all the time’ or ‘I have an anger problem’, that is not good enough. They need to also understand why they’re feeling that, what is it they are responding to, and to recognise that sometimes it is because something isn’t just, or it isn’t right. That’s a much more critical and difficult conversation to have. But you know, kids love that,” she says. “Human beings are natural philosophers … they have a natural drive towards liberation.”

Even now, Van Deurzen swims against the cultural tides. She is wary of modern therapy speak, the impulse to diagnose others with narcissism or dismiss them as toxic. “You create an atmosphere that is anti-therapeutic; an atmosphere of fear and terror about human existence. So I do think we need a counter-cultural movement to reclaim our freedom in that respect and to say: ‘Well, we’re actually a lot more robust than we think.’” She says the role of a therapist in this environment is to talk to someone about their uncertainty over who they can trust, or the pain they have experienced, and to explore how they might regain their courage. “These are the small philosophical discussions that people desperately want to be having because they want to understand how to live, instead of living their lives thinking: ‘Oh, red flag here. Red flag, there,’” she says.

How does Van Deurzen understand the UK’s mental health crisis? NHS England figures suggest that more than one in five adults have a common psychiatric condition, and one in eight are taking medication for mental illness. “There is no discourse that allows you to understand what is happening to you in any other way than by thinking there’s something wrong with me,” she says. She believes that “we have focused so much on materialistic pursuits and scientific pursuits, but we’ve lost track of the human spirit … people do not know where to turn to figure things out”.

Van Deurzen remembers that in the 1950s and 60s debates about philosophical issues were often broadcast on TV, but philosophy has retreated from public conversation, and in many countries, religiosity has also declined. “With the disappearance of the structures of religion we have thrown the baby out with the bath water, the baby being an awareness of your emotional, mental and spiritual wellbeing, and how you might live your life in such a way that it feels meaningful and coherent and makes sense to you, and that you know how to be a good person.” She sometimes gives her clients reading lists, and often recommends Rollo May’s writing, as well as Erich Fromm’s The Art of Loving and Paul Tillich’s The Courage to Be.

Does she believe, then, that society is hungry for more therapeutic wisdom? “You said the taboo word!” Van Deurzen exclaims, throwing up her arms with excitement. A therapist is not supposed to speak of wisdom because it undermines the ideal of equality between the analyst and the analysand, who should be puzzling over problems together. “I’ve thought about it a lot: do I claim to have wisdom? And I thought it’s better to aim for wisdom and to be aware that wisdom is something dynamic and in motion,” she says.

But Van Deurzen has “no compunction” over asserting that society needs a heavy dose of the w-word. “We need to bring wisdom back into the world,” she says. “And that is what the existential movement is for. It’s bringing wisdom back into the world, thoughtful ways of living your life, and understanding how to be in a community, and how to create a civilisation that has a future – for goodness’ sake! – and that is going somewhere instead of destroying itself.”

Beginning to Live: The Art of Existential Freedom be Emmy van Deurzen is published by Allen Lane on 14 May. To support the Guardian, order your copy at guardianbookshop.com. Delivery charges may apply.