@leer67 sounds like you have decided to “wear my shoes”.
I understand those thoughts and the feelings you expressed. I would guess that many of us on here can relate.
Ten years ago when I was 64, I was 50 pounds slimmer, had a personal trainer at the gym, and felt marvelous.
Now, as you alluded to, our lives have changed and we don’t want to be that old sick person in the mirror.
Things happen. Good, bad, or indifferent, things happen to all of us as time goes on. I’m stuck with a cane and a walker. However I survived a very rare autoimmune disease a few years ago. I still suffer from fibromyalgia, occipital neuralgia, osteoarthritis, polyneuropathy, and Vasculitis.

What can we do about this new us, and how it makes us feel? We are allowed to mourn our former selves. However, we can’t get stuck there.
We can think about all the good things that remain steady in our lives I guess.

Wishing you a happy weekend!