As Manuel Neuer eyes a 40th birthday on the pitch, former Bayern legend Oliver Kahn warns: playing three competitions at that age is physically unsustainable. In this deep dive, I break down the biomechanics of aging athletes, the psychological weight of legacy, and why even legends must choose when to rest. Drawing from data, personal experience as a former analyst, and insights from global football culture — this is not just about Neuer. It’s about what greatness demands when time catches up.