Depends on what you're asking your body to do. I played soccer pretty intensely when I was younger. The timeline went something like this: late teens to mid th

Depends on what you're asking your body to do. I played soccer pretty intensely when I was younger. The timeline went something like this: late teens to mid thirties, top physical form mid thirties, losing the proverbial step (pros retire at this point) mid forties, it's obvious you can't keep up with the youngsters anymore. Even your superior experience can't bail you out. mid fifties, it's obvious that if you don't quit you'll be seriously hurt.