70 y.o. here. I ride on and off-road (less off-road, mostly due to lack of as many trails where I now live). One of my other forms of exercise is attending a Silver Sneakers class at a local gym. Some of the seniors which also attend would not be capable of riding, due to injuries or other reasons. A friend, who is 83, has been lucky enough that even with a knee replacement, has been able to continue to ride. Even rides up some steep hills which I've seen many walk! So I'm always thankful for each time I'm able to get a ride in, and happy for those like my friend who is still able. Amazing what we now give thanks for, that we used to take for granted.