Here's a sobering thought. What if I haven't done it yet?
Good thing I don't believe in predestination, or I'd get the heebie jeebies right about now. Imagine, if you will, that it's encoded into your DNA to do one of each. That you're on this planet to do one really good thing, and one really horrible thing. You don't know what they are, but you gotta do 'em. There will be a big gaping hole in the fabric of reality if you don't. You may go your whole life without knowing, until the very end of it, when you suddenly realize that you did them both when you were six. Or you did the Bad Thing when you were seventy-four and the Good Thing when you were eighteen. Or you did the Bad Thing when you were fifty-one, and--and you haven't done the Good Thing yet. You haven't done the Good Thing, and you're running out of time, and what if it's not going to happen until after you die? What if you're going to donate your body to science, and because of you, some kid in medical school will grow up to, I dunno, cure Shy-Drager syndrome or something?
Anyway, like I said, I don't believe in predestination. And I reckon all of us do both good and bad things, just because we're human beings. But wouldn't it be awesome if, instead of yearning to be rich or thin or powerful or famous, more of us yearned to be nice or wise or smart or compassionate? If I could convince a few people that that would be a better path, I'd settle for that being my One Good Thing. I really would.