The THz band (0.1-10 THz) is emerging as a crucial enabler for sixth-generation (6G) mobile communication systems, overcoming the limitations of current technologies and unlocking new opportunities for low-latency and ultra-high-speed communications by utilizing several tens of GHz transmission bandwidths. However, extremely high spreading losses and various interaction losses pose significant challenges to establishing reliable communication coverage, while human body shadowing further complicates maintaining stable communication links. Although point-to-point (P2P) fixed wireless access in the THz band has been successfully demonstrated, realizing fully mobile and reliable wireless access via highly directional communication remains a challenge. This paper addresses the key challenges faced by THz mobile networks, focusing particularly on the behavior of multipath channels and the impact of human body shadowing (HBS). It presents the environment-dependent characteristics of multipath clusters through empirical measurements at 300~GHz using a consistent setup, highlighting the need to account for environmental factors in system design. In addition, it presents a motion capture-based approach for precise measurement and prediction of HBS to enable proactive path scheduling and enhances link reliability, offering key insights for robust THz communication systems in future 6G networks.