I'll be 52 this November. Have been coding mostly as a hobby since '83, with peaks in programming intensity at different stages of my life: sometimes to scratch an itch and sometimes doing some contract/consulting work. Still try to hit the computer whenever I can, but my health's been letting me down lately - nothing too bad, but it's been affecting the focused time I need to do programming right.
So now when I sometimes think of my mortality, the thing I regret is the programming I can't do when I'm gone. Or maybe there is programming after death? I'm hopeful. :)
In the meanwhile, the free time that's opened up from not programming as much is being wisely invested. I'm working hard on my guitar, and before I go dammit, I'm going to shred like a pro!