Jay Shetty shares eight psychological and life lessons he wishes he had understood before turning 30, aimed at saving time, energy, and emotional stress. Drawing on research in psychology and human behavior, he explains concepts like the spotlight effect, the effort heuristic, socio-emotional selectivity, decision fatigue, social contagion, burnout, and affective forecasting. He then turns these ideas into practical guidance on how to think about other people's opinions, productivity, friendships, discipline, fear, community, meaningful work, and the unpredictability of future happiness and pain.