They go hand in hand. In most professions you need to be about 40 to be competent. When you're young this doesn't seem likely because you don't see many competent middle aged people: that's because they're up in management actually running things. Unfortunately we start aging mentally around the same age, and at 60 we're not really capable of creative work anymore.

So we live 80 year lives, but with only about quarter of that really giving all we're capable of, and a fair share is being dedicated to raising children. Living an extra 20 years isn't a perk - it literally doubles our most productive years. Living an extra 40 years with most forms of dementia fixed? That's almost unimaginably more productive, and unimaginably richer. Both on an individual level (working+learning more = earning more), but as a society.

You mentioned "when it's more worth living". Not sure what context you're coming from, but life is a lot more worth living in its second half, simply because you know more about how to live it, and have the means to do it. The only problem is you're getting old and senile.

Edit: please don't downvote somebody asking questions.