This is beginning to sound like a symposium on gerontology or a bunch of "old guys" sitting around in a "facility" discussing their various and sundry ailments.
As an OLD guy with a grey beard, who has his own compliment of aches and pains, I am certainly not trivializing various health issues and age-related disabilities. The problem is, as I see it, is there's enough AGEISM out there, so that we do not need to practise self-imposed ageism and convince ourselves that we can't carry on with all of our favourite activities just because we have to approach them a bit differently. We may have to go a little slower or lift a little lighter but that is no big deal.
We see images of Ansel Adams and his contemporaries schlepping around an 8x10 view camera and working atop his wooden-clad station wagon. Nowadays, we have equipment that is comparatively lightweight that can produce view-camera-like quality in the hands of a technically savvy photograher. I have a "Featherlight" brand stepladder that I can lift with 2 fingers of one hand. And..,. is it simple common sense that each of us will select equipment that we are able to manage as to size and weight. We certainly would not buy shoes or clothing that does not fit nor should we buy or continue to use the equipment we can not manage. There is plenty of good gear that comes in small packages! If you can handle a heavier or bulkier camera and find it easier to steady and leave- more power to ya! If you can't, think of it this way; for folks, how to have mobility difficulties there and all kinds of mobility aids, many of these things can be adapted to your cameras.
As for physical and mental fitness- you don't need to run marathons at 70 or 80 -years old. You don't need to go to the extreme crazy diets or play tackle football every day. All you need to do is walk, stop taking the car to the corner store, keep active, do normal exercises like household chores, gardening, fixing and constructing stuff, and continue your favourite sport, if you can, knock off the smokes, booze, and recreational drugs and do not eat 3 meals a day at Mc Donalds or Taco-Bell! Photography is great for mental exercise- you need to figure things out, make calculations, be creative and resoursful, solve problems, use your visual perception, and get out of your house a do stuff!
Ageism is just as bad and widespread as racism, sexism, xenophobia, and all the other prejudices. Problem is, there's not very much pushback by organized groups or associations advocating for older folks and it ain't on TV every day.
Just member, a rocking chair is lousy camera support and it won't do yuro videography any good either!