Actually, I exercise a lot. What I don’t do, is pound my feet against concrete and asphalt over and over.
Recently (at age 73), I took it up again but using a new (old) method, the Maffetone Method.
I now run very slowly--actually run/walk--in the aerobic zone making sure I midfoot strike. I'm very slow but it feels wonderful and I don't have any problems...yet.
The damage to feet and knees comes from heel strike, which bangs the feet hard on the pavement or trail, causing the ankles to swivel and sending schock waves to your knees.
Midfoot and forefoot strike is called natural running and is so easy on legs, knees, and feet. Obviously, if something starts to hurt...stop for a few days.
I tried running every day but that doesn't work...legs got too tired. I now run 4 miles per run (walking only a little) 3 or 4 times a week. I don't mind that I am VERY slow because my feet and legs feel great.
I still bike on alternate days and have found that my running has even improved my biking (speed and vigor up).