When one of Karen Stewart's clients starts complaining about their job, she cuts them off mid-rant. As they vent about their infuriating boss, irritating coworkers, and gnawing urge to quit, she asks a pointed question: “What would happen if you woke up tomorrow and received a letter that your services were no longer needed?”

“You immediately see their face change,” says Stewart, a clinical psychologist in Los Angeles. She follows up with another hypothetical: Would it really matter, she might ask, if their coworker microwaved fish at noon? If their boss scheduled pointless 4:30 meetings? “You can literally see the cognitive transformation,” she says. “They start thinking, ‘Well, actually, it’s not that terrible.’”

This “what-if” technique, which Stewart practices on herself as well, is called mental subtraction. It’s not about focusing on loss, she clarifies; rather, it’s about rediscovering the value of a relationship, job, misbehaving pet, or anything else that’s irking you.

Here's what to know about mental subtraction—and how to do it yourself in about a minute.

What the research says about mental subtraction

The technique has a cinematic origin. The most-cited evidence comes from a 2008 paper whose authors borrowed their premise from It's a Wonderful Life, the film in which the protagonist, George Bailey, is shown how much worse off everyone would be had he never been born. Across a series of experiments, researchers asked participants to imagine that a positive event in their lives had never happened. Those participants often reported greater positive emotion than people who simply reflected on the event itself.

Mental subtraction works by interrupting a long-documented psychological process called hedonic adaptation, says study author Minkyung Koo, an assistant professor of marketing at the University of New Mexico's James & Gail Ellis School of Business Leadership. "We naturally get used to life events, whether they’re good or bad.” That adaptation is useful after bad experiences—the sting fades over time. “The downside is that positive events also become familiar and no longer bring us as much happiness as they once did,” she says.

That's what mental subtraction targets. “Imagining how a positive event might never have happened helps people see that event as less inevitable and more surprising,” Koo says.

How mental subtraction is different from gratitude journaling

So isn't this just the mental version of gratitude journaling? Not quite. “Most people think of gratitude as listing things they're thankful for,” says Suzie White, who teaches a science-based well-being course called Happiness in Action at the University of Cincinnati. “Mental subtraction takes a different approach.” And that difference matters, because the same adaptation that dulls our good experiences can dull a gratitude practice, too. Roxy Zarrabi, a clinical psychologist in Chicago, says some of her clients get so used to writing gratitude lists that the exercise loses its punch. They "feel like they're struggling with connecting to the feeling of gratitude, and they might feel frustrated instead,” she says. Mental subtraction, on the other hand, "counteracts that tendency.” While a gratitude list reminds you that you value something, subtracting it makes you imagine what its absence would cost “without actually having to go through it in real life.”

The original studies measured people's reactions immediately after a brief, one-time exercise, Koo notes, and didn't test how long the lift lasted. She'd rather people treat mental subtraction "as a useful psychological tool rather than a proven long-term happiness intervention.” But the core insight has held up. “People often underestimate how much they’ve adapted to the good things in their lives," she says. “By occasionally considering how those things might never have come about, we can see them with fresh eyes and appreciate them more fully.”

Mental subtraction works best when you're fed up 

The moment you're most annoyed is when mental subtraction is most useful. Those flashes of frustration, Zarrabi says, are exactly the cue to try it, “because sometimes in those spaces it's hard to recognize how quickly things can change.”

When a client keeps griping about a partner or a job, Stewart doesn't announce that they’re about to try a new exercise—she just slips in a "what if." The thing being complained about, she's found, is usually something the person would hate to actually lose. Picture the partner who's always running 20 minutes late: Subtract him entirely, and the tardiness stops looking like grounds for a breakup. “A majority of the time, we don’t want to eliminate the thing that we’re upset about," Stewart says. "We just want something specific to change."

There's a bonus effect, too. When the exercise reminds people what a relationship is worth, they tend to act on it by giving a compliment, a thank-you, or some other small gesture. The other person often responds in kind, which makes you more likely to keep up the gratitude. "It can be a domino effect," Zarrabi says.

How to do it in 60 seconds

Mental subtraction doesn't require an app, journal, or a special setting—just one minute and a little imagination. Here's how to put it into practice.

Catch yourself complaining

The easiest entry point is a gripe you're already having: the partner who never does the dishes, the boss who's always late, the dog that chewed through yet another pair of shoes. Or simply choose one person, relationship, or stroke of luck that matters to you. Stewart once worked with a man who couldn't stand his job, so she had him picture losing it: not just the paycheck, but the free underground parking (a rarity in Los Angeles), the deep breath he took before his daily Starbucks run, the catered lunch every Friday. "You watch them have the transformation of, 'I hate my job, I hate it,' to, 'All right, it doesn't suck,'" she says.

Subtract it

Now do the actual subtracting. Take a few breaths imagining that the person, job, or other thing never came into your life. The trick, Koo says, is to genuinely imagine the absence rather than just admire what's there: “The 'wrong' way to do the exercise would be to simply think about the positive event itself or to reminisce about it,” she says.

Stewart often nudges clients toward the version where the choice isn't yours—the boss hands you a termination letter, your less-than-ideal apartment lease doesn't get renewed—because losing something on your own terms and having it taken away instigate very different feelings.

This is when the things driving you crazy can start to seem a lot less important. Take the barking-round-the-clock goldendoodle: Yes, he ruined your favorite leather bag and an expensive pair of heels, but subtract him and you also lose the daily walks, fresh air, and exuberant greeting when you walk through the door. Or the parent who drives you up the wall—imagine not being able to pick up the phone and roll your eyes at them tomorrow. You might be surprised, Stewart says, by "how much you would miss that annoyance."

Come back to the present

Return your attention to what's actually in front of you. The circumstances haven't changed, but your perspective might have. White recommends anchoring the whole exercise to a daily habit so it sticks: pair it with brushing your teeth, making coffee, or your morning commute. "Attaching it to an existing habit makes it easier to remember," she says.

Act on it

Don't let the appreciation evaporate. The point isn't just to feel better for a minute—it's to do something with what you noticed. Sometimes that means a small gesture of gratitude: a compliment, a thank-you, a scratch behind the dog's ears. But Stewart pushes clients further, toward fixing whatever's actually fixable. If your partner's coat is always on the counter, that's a conversation, not a life sentence. “I gotta be honest, it's been making me crazy—but I want us to figure out a way,” she offers as a model. If you genuinely dislike your job, the gratitude buys you the calm to update your resume instead of quitting in a huff. The goal isn't to talk yourself out of every grievance, she says. It's the mental clarity to tell the difference between the stuff worth fixing and the stuff worth being grateful for.

The point, Stewart says, is perspective. We tell ourselves we're in control—that we could quit the job, end the relationship, move out tomorrow. But that's very different from having those things taken away from us. "If your partner breaks up with you tomorrow, your boss fires you, your pet runs away, your car breaks down, your landlord kicks you out, you'll drastically change your perspective," she says. Mental subtraction just lets you get there first, before anything's actually gone.