'Old' is a strange thing - the longer you live, the further away 'old' is.
And of course 'old' doesn't mean incapacitated, useless or miserable. My 93 year old neighbour cares for his disabled wife full time, with only the nurse twice a week - one hour each time. He looks after the house and garden, does all the shopping and most of the housework. He is not 'old' in the sense you mean.
When I were young, 30 was old. When I was 30, I was young and 55 was old. I'm well past 55 and still not old.
His disabled wife is in her 80s and frankly isn't very able bodied. She lives life to the full and sucks every ounce of enjoyment out of every day that she can.
This couple have an enviable zest for life and are a good example that people should be labelled 'old' or 'disabled' as objects of pity,