I believe the problem is that there's denial about old age health and infirmity. Being fit and healthy is a good thing but it also can be temporary.
I'm not inspired by training in spite of health problems so much as inspired by 40 something years of training, and the reflection of that training in his Aikido. I mean I stopped playing rugby after 15 years because it was destroying my body..
I know my sensei was in much better shape when he was younger. He claims his Aikido has improved with age. Since I wasn't around back when he was a "young turk" I can't compare, but what he has right now is enough to be overwhelming to me and most other people I've trained with.
hell he still dominates in ne-waza against people a third his age, chuckling as he applies the lot of dirty tricks in his bag.
the health issues, well, they're there, but they're not a huge problem. As all of you say, no one's perfect. I can still learn a lot.