The human body (like most fit organisms) is antifragile. It needs to be challenged. In this context, people who think "ooh that hurts I'll never do that again" and carefully avoid discomfort find that, by middle age, they can't do anything, and everything hurts. Meanwhile people who think "ooh that hurts, I'd better practise it until it doesn't" are still fully functional into old age because they push their bodies in the right way, and so their bodies stay strong.
Don't get me wrong, the latter group still hurt. Getting old sucks. But their bodies work.
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