Compounding is usually discussed in financial contexts — the idea that returns on investment generate further returns, creating exponential growth over time. But compounding operates identically in health. Each healthy choice makes the next healthy choice slightly easier — improved energy makes exercise more accessible, better sleep makes food decisions more rational, regular movement reduces stress that drives poor eating. The reverse is also true: each unhealthy choice makes the next one more likely. The compounding of poor choices is what people experience as the health crisis in middle age that seemed to arrive suddenly. It was building for decades. The strategic insight is identical in both domains: start early, be consistent, and let the compounding work. The earlier you start, the less effort each unit of improvement requires.