Although I'm 57 I might as well be 27 for the amount of time I've spend developing and building start-ups. I played saxophone professionally until I was 40, then gave it up as just too much work. I must be a glutton for punishment.
I dunno. After spending a few years sitting at a keyboard with letters on it, workin' 'til two where they close the joint with the old "You don't have to go home, but you can't stay here," seems kind of attractive. Or would, if there weren't those little wetware alarm clocks always working their particular magic... (And I could still stay up that late on a consistent basis..)