MOVE A MUSCLE!
The older you get, the more you should be into fitness. I might be old, but I feel young, you know? My stretching routine helps me do that. We all lose a little of our flexibility with age. And our muscles lose their strength. You must stay active and work on these things. I'm told my stretching routine is famous. I just started moving around one day to warm up. And it worked, so I kept it. It's as basic as that.