I've had CFS for 16 years. Even after this length of time, I still am surprised and frustrated with my response to exercise. What I think is so strange is how when I do the exercise, it's actually enjoyable. I used to be a dancer, so it feels great to stretch and move around. But I will do 5 knee bends and 5 waist stretches and stop. I would never even think of doing anything aerobically. Even though I feel fine, it's thee next day that I really suffer. I am in bed, running a low grade fever and unable to even get up to feed myself. I had foot surgery, and I can not even do foot exercises without a bad relapse. I had a foot massage and pointed my foot 20 times each several ways and then for a week I couldn't get out of bed. Obviously, my conditioning is getting worse, so I really need to exercise. But it's like quick sand, if I struggle to exercise I sink quickly, if I just try to rest, I slowly sink into deconditioning. I still don't understand why PWC's can feel fine on the day of exertion, but a day later crash.