You're no longer dreaming of flying.

"You wonder whether your swing could flip over the metal bar at the top, swing you all the way around, and throw you to the ground, bruised and broken. When you were a kid, you thought it could happen--but you weren't afraid. All grown up, you know it can't happen--but you're filled with fear. You swing slower, instead of pumping for the sky. You don't jump off-- you slow yourself to a stop. You'd never fling yourself into the air midswing, because you're no longer dreaming of flying. You're just worrying about how you're going to land."
--Robert Wasserman, 'Envy'