When you get to this age, most of us are just happy to be still alive .
With respect, that way of thinking is really flawed.
Of course, as we age, the risk of ill-health increases. But in the fortunate absence of illness, we can aspire to far more than 'happy to be alive'.
I train intensively, every day - weights, HIIT, spin, running. I see & train with older women who are in great shape, though perhaps modify aspects of their exercise. I wish there were more though. I follow several older women on Insta in the US who are in amazing shape (older men too) - the thinking and encouragement for this in the States is much more established.
I'm sorry about your friend. My dad is a similar case - a very active, fit man his whole life, but developed a complex multi-faceted neurological condition in his last decade & was ultimately physically very limited. He kept going though! He persisted with activities that he wasn't really able for, but he was right to do as much as he could.
It's made me determined to do what I can as long as I can, fitness-wise. We don't know when ill-health will challenge us - but there are many people your age in great shape, running, lifting weights, training. The key advice is - don't stop - in fact, you're encouraged to do more, as you age, especially in retirement.