I'm thinking about trying Tai-Chi or Yoga as I get older. It just makes sense to me to keep moving in a regular stretching manner every day.
For now I'm not so ancient as you (only 58 ;-) but I still ride to the train station every morning (all winter long), I "stand" on all the hill rides (they're short), and I still purposely "bound" up the stairs at home (try, anyway).
I'm OK with getting old, but getting to the point where I can't ride anymore will hurt.