As someone who has a milder form of ME I can fully confess that reading these forums gave me an unrealistic fear of exercise. I consequently reduced my exercise and my symptoms worsened.
I wonder if you would mind expanding on that please, because I can't understand how reducing exercise levels could worsen ME symptoms? I assume you continued to participate in a range of daily activities, as it's almost impossible to entirely stop daily activities, unless severely ill. (I mean, I can't imagine that you stopped activity altogether and took to your bed for months on end?) If you continued with daily activities (e.g. walking to the sofa, showering, walking between rooms in the home, picking up your post, doing occasional laundry, making a cup of tea a few times a day, walking to the garden or to the local shop, etc.) then you wouldn't have suffered from any long-term muscular deconditioning, and I can't see how your health would have been adversely affected.
Do you specifically mean that 'exercise' rather than 'activity' helped improve your symptoms? If you mean that actual 'exercise' improved your illness, then it suggests that you don't have 'ME' as defined by CCC & ICC, or 'SEID' as defined by the IOM, or CFS/ME as defined by NICE, as they all require a post-exertional exacerbation of symptoms for a diagnosis. If your illness responds positively to exercise, then obviously that's great, but it suggests that you don't have ME, but that you experience fatigue due to some other mechanism or illness. (
Edit: I never find it attractive to question people's diagnosis, and perhaps I'm being unfair to put these questions to you, but your comment baffles me.)
As an aside, i've always struggled to reduce my activity levels; As soon as I'm feeling slightly better I go bounding off and cause yet another relapse. It took me years to learn (the hard way) to slow down. I think most of us struggle to reduce our activity levels such that we avoid causing relapses.
