It’s been a year so I hope you have found some answers and gains since when this was posted, but I wanted to weigh in as a fellow post-viral chronic fatigue patient. ME/CFS is a huge umbrella term, and there’s still so much that isn’t known about the underlying factors. What you’re describing is a common experience for our patient population. If you look up GET (graded exercise therapy) for ME/CFS recovery, you’ll see that there is a lot of discussion about the potential harm of too much physical activity during recovery. The new NICE guidelines recommend no GET at all. I personally found that I could do what you’re describing and keep my activity low (pilates has been great!), but I had to tune in to my body. The trick for me has been the pacing: not doing so much physical activity that it results in an energy crash, and taking time for recovery between sessions. And yes, shifting from “training” to things like walks, pilates, paddle-boarding, etc. Equine-assisted rehab was a big win! It’s worth noticing if your hr and bp is behaving normally, as dysautonomia is a common comorbidity. And shout out to you for figuring out how to take it slow: it takes a lot of mental toughness not to push too hard and play the long game.