My grandmother is 91 and still does kettle bell workouts. She has dementia which sucks. But if it were not for that, she could still do all sorts of stuff. She was playing golf with her club friends up until a few years ago until onset of dementia. She skied well into her 70s. An older friend of mine is 80 and his morning workout is to play 18 while walking the course. He looks 65.
I decided to get into shape a few years ago when I turned 45 after several years of being out of shape because I want my 50s to 80s to be as good as they can be. I have seen to many people in their 50s that are in awful shape and unable to walk up a flight of stairs without getting short of breathe.
I am not nearly as worried about longevity. As a believer, not worried about dying. But I do not want to be an invalid or unable to do the things I love outdoors. To me, health is about putting yourself in the best position possible to have quality of life. Very hard to do if you are obese, eating garbage, and inactive.