You can live one full human lifetime without doing any at all.
Muscles start atrophying after as little as one week not using them properly.
I asked doctor and speaker at an MECFS event a similar question, in relation to severe MECFS, whether the patient is completely bed bound. They said that although muscle atrophies, that the cells themselves don’t die. For someone who is completely bed-bound, they said that this is good news because they can prioritise pacing and if they recover later, can their muscles.
This was part of a much wider context which I’ve omitted here but as a fragment of information it might be reassuring to anyone who finds themselves (hopefully only) temporarily debilitated.
I don’t think you should think about minimizing exercise. Other than the health and longevity benefits, being fit can make you feel superhuman.
Imagine carrying extra reserves of strength and energy. Life will feel easy. You can do things others can’t like getting out of tight spots with a muscle up, carrying someone and running during an emergency, running to catch a bus etc.
Exercise greatly improves balance and reflexes. The chances of you slipping and falling awkwardly breaking bones or dying will be much lower.
It also improves your appearance greatly. As someone who went from frail to fat and then fit, I can tell you the difference is huge. People treat you much better and give you lots of attention.
