The video explains the physiological and psychological impacts of prolonged stress and fatigue on the body. When cortisol and other stress hormones are elevated due to continuous stress and lack of rest, they can lead to a decrease in testosterone levels. This hormonal imbalance not only affects physical health but also alters brain function and psychology. The nervous system processes influenced by these hormonal changes can lead to different thinking patterns and psychological states, highlighting the importance of managing stress and ensuring adequate rest to maintain hormonal balance and mental well-being.