I used to exercise a lot before I graduated. By exercise I don't mean walking, which we were compelled to do in those days due to not having cars. I had to walk about a kilometer to catch a bus to college, and another kilometer on my way back. Apart from that, a lot of walking was done to buy groceries. So I managed to remain slim, in fact for a few months I had to consume a lot of supplements to increase my weight. 

As I said, aside from walking, I did calisthenic exercises as well. I used to do weight-lifting and spring pulling to strengthen my arms. My weight is almost the same as it was when I was in college (around 70 kg). As the years went by I gave up calisthenics and even reduced my walking considerably. For a time I had a stationary bicycle. I used to walk with my wife and children a lot in the 1980s, as a result of which our neighbors thought we were a bit crazy. Even today, I take a forty minute walk with my wife almost daily, but nowadays we see many couples doing it also, so I suppose people don't think it odd (although the security guards and servants must be wondering why we do it).

For years now I've had back ache. Until 30 years back I used to lie on my back on the floor and do exercises to reduce the lower back pain. After a time I gave it up. Now I've taken it up again, and I must say that it works even though I started only a couple of weeks ago. However, some pain is still there when I get up in the morning. I hope I'm able to go on until it's in control, though I don't think I'll be able to eliminate it entirely. This year I stopped exercising my arms for a time (in the month of fasting), so I developed a frozen shoulder. I couldn't raise my right arm at all. It took a month of exercising to return to normal. It looks like I'll have to go on exercising until the day I die.