The trick is that he has stayed active and has not let body deteriorate too much. If you keep active and do not do anything too destructive of your body, and are not too unlucky (like getting a disease that cripples you or getting hit by a bus), you, too, can be active when old.
For many people, this means watching what one eats, as well as getting enough exercise. Most Americans do not do that, and so they cannot match Mick Jagger's activities at his age. He would not be able to dance around for 3 hours if he were carrying an extra 100 pounds of fat. Nor could he dance around for 3 hours if he did nothing but sit on his couch watching TV or posting online.
So, the way to be able-bodied when old is simple. But most people will not do what is necessary and therefore will not be.
For many people, this means watching what one eats, as well as getting enough exercise. Most Americans do not do that, and so they cannot match Mick Jagger's activities at his age. He would not be able to dance around for 3 hours if he were carrying an extra 100 pounds of fat. Nor could he dance around for 3 hours if he did nothing but sit on his couch watching TV or posting online.
So, the way to be able-bodied when old is simple. But most people will not do what is necessary and therefore will not be.
"A wise man ... proportions his belief to the evidence."
— David Hume, An Enquiry Concerning Human Understanding, Section X, Part I.
