I'm 64. I go to the gym 3 times a week. I work out on the arm muscle machines to get rid of some arthritis in my shoulders and I'm up to 50-70 pounds on them. 110 pounds on the abdominal muscles and 140 on the abductors and adductors. I alternate a stationary bike with walking uphill on a treadmill and get my pulse into the 120s.
I'm not an athlete but I seem to be as strong or stronger than most people my age. I've never been a runner but I can walk a couple of miles at 3mph without being out of breath and I can walk 4mph if I have to.
Aside from the arthritis my worst problem is a torn cartilege in one knee. If I climb more than one flight of stairs per day it starts to hurt, but that's about the only impact it has on me. I go dancing every week or two and bounce around with the young people. I'm a musician and I haul around a 120-pound amplifier.
The biggest part of staying fit at my age is being limber. You have to do Eastern style exercises--stretching--not just Western style aerobic and muscle-building stuff.
My resting pulse is about 65, my blood pressure is 130/75, my cholesterol is just barely in the okay zone. I could stand to lose five or ten pounds but who couldn't? I've never dieted and scared my body into developing an efficient metabolism, so I can eat quite a bit. The Four Basic Food Groups start with Chocolate and Pizza.
Best of all, my brain works. When that starts to go it doesn't matter what kind of shape the rest of you is in. Just doesn't matter at all.