Just want to add, for some there is the issue of post exertional malaise (PEM) when cardio becomes counter productive. Those can often still weightlift without

Just want to add, for some there is the issue of post exertional malaise (PEM) when cardio becomes counter productive. Those can often still weightlift without triggering PEM. This is predominantly how I managed it for most of my life and worked ok until the covid vaccine triggered another setback. It's directly linked to stress, I think the predispositions are linked to not being able to ameliorate stress so anything that helps manage stress will help.