It's called aging and genetics and there are many, many sedentary seniors out there who are way older and will outlive many athletes. You are in some control with diet and exercise and lifestyle choices but something in you will kill you eventually. I will keep saving for retirement but generally don't plan for longer than a decade at a time. Anything can happen at any time and if you grow old spending too much time with your eyes on the ball and not in your hands, what is the point?

What sucks now is that exercising too hard could kill him faster or damage his heart more than if he took it easy and lived a sedentary lifestyle from here on out.