Via Instapundit, the lessons from having children.
Obviously, if you don't want kids, having them won't make you happier. But if you already know you want kids and you're worried that they'll ruin your life and destroy your career, think again. Kids don't just bring a lot of joy to your life by being weird and funny and yes, annoying and loud, too. Kids also force you to decide what's worth your time and what isn't. Kids force you to focus on the things you love (yes, like your kids! But other things, too!) and to invest in those things with all of your heart. And as your kids grow up, those three seconds of free time expand into three or four hours of free time that you truly enjoy. Kids teach you how to enjoy your time, in other words, both by modeling enjoyment (usually by gnawing on something expensive or squealing at the top of their lungs) and by squeezing your free time down to nothing.