From Freddy and Fredericka, by Mark Helprin:
Something happens to the body at fifty that at twenty you can't imagine, at thirty you don't suspect, and of which at forty you have just a hint, but cross that bridge when you come to it. You'll be a different man then. You'll forgive yourself. The chase will be over and you'll have learnt to love the world for what it is and to see yourself for what you are. It happens to everyone, even to kings.