I'm 40 and my dad is 72. A couple of months ago he had an emergency spine surgery because apparently a spine bone was clinching a nerve. Before the operations, in a couple of weeks he started losing feeling in one leg.

After the successful operation, the doctors told him that the fact that he could still walk was product of his VERY active life, and that he has athlete's body. He has always been super athletic: He was in the Olympic (Mexico) gym team when he was in his 20s, later he was a scuba diver and always did a lot of exercise.

I have always been the opposite (computer programmer, nerd, etc). It was after this that I decided to fully dedicate to improve my body (I walk 90 minutes 3 times a week, and row 30 minutes 3 times a day. I am planning to start doing weight after I get some muscles with the current exercise). I've decided that what I am dedicating my next 40 years is going to be exercising my body and being fit.