My grandmother used to say that old age doesn't come itself - in other words that it brings ailments with it.
Of course I didn't understand that when I was younger. How could I? I didn't even realise that I was young. We don't. Being young means that anything is possible, that life stretches ahead, and if 'this' doesn't work than 'that' might, and all we have to do is try. We don't even know that this attitude is time-limited when we are living it, and it can come as a shock when that phase of life ends.
I don't expect my children to understand what my life is like these days (somewhat limited by health-related mobility problems) and I don't really want them to. I am there when they need me, and will spend as long as it takes making sure that I can do whatever they ask. I have time that they don't for that. When they come to stay, I organise things so that I do as much as I can (and I'm by no means incapable) but opt out as gracefully as possible of things that I would impede. I am not a burden for them to bear, and I won't be for as long as I can possibly avoid it.
I am a bit limited physically, but not mentally, and have organised my life so that I get as much mental stimulation as possible, and one of the upsides of Covid is that Zoom has opened up so many possibilities in that direction. This means that I have something to talk about other than what happens at home, and I do my best to be 'interesting', even if I can't be as physically useful as I might have been in the past.