I have a good friend that is almost 84. In our social group, if he asks for help, you better buckle up... you are about to have the hardest day of work you have ever experienced. My family lovingly calls him the "Terminator". He has managed this strength by never, ever, stopping. At least that is the excuse he has offered. I try to follow his example and never stop. So far at 49, I cannot keep up, but I do keep trying.