It turns out that humans are evolutionarily predisposed to react and avoid threats, just as zebras do. We should relax most of the day and only run like crazy when danger approaches. Zebras have acute stress reactions (physical threats) from time to time. In our country, on the contrary, the chronic stress reaction (psychological threats) rarely reaches such magnitudes as in a zebra, but it does not disappear anywhere. Zebras die quickly, falling into the clutches of predators. People are dying more slowly: from coronary heart disease, cancer and other diseases that arise from chronic stress reactions. But when stress is predictable, and you can control your reaction to it, it no longer affects the development of diseases so much. One of the most authoritative and world-famous books on the psychology and physiology of stress.