Children.
Otherwise you're just counting down the clock until your passing, eating limited food, breathing limited air, stroking your ego, triggering your body chemicals; hedonism. Plus you've evolved with the biology to constantly push you towards mating. And if you don't, there will always be that part of you unfulfilled, a piece missing, a task uncompleted, a niggling thread of failure, although you can bury it so it only affects you indirectly and you can then rationalize your problems as being attributable to something else unrelated.

Other than that, no matter what you do in life, no matter what you produce for society, it ultimately doesn't matter (except to you to the degree you can convince yourself) unless you pass on your DNA.

Unless you're religious. Then you need to because (insert your god here) said so.



With what I'm willing to do for other people, I can't think of anything better to do.