Try to avoid, at least for the moment, any form of exercise standing up. You could use small weights while sitting or do 1-2 crunches or even attempt one push-up but avoid any standing exercise, we usually don't tolerate them expecially when so reactive as you sound. A person I know, without CFS, used to exercise three times a week for 40 minutes each workout. Now he converted to 5 minutes everyday. According to him is as strong and fit as ever so there was no change in splitting up the exercise-load of a day in daily mini-session. So for example instead of doing 5 knee bends you could do 1 knee bend everyday. But for the moment avoid exercising while standing up, you should suffer less next-day exhaustation. Also I never tolerate exercising in the morning, in fact the less I do in the morning (including talking) the better I feel slightly better in the evening so usually I do more around 6-7 pm In the morning PWCs have many post-night symptoms that worsen their condition including: dehydration from bad fluid ritention, low blood sugar from impaired sugar metabolism, low endorphine from impaired sugar metabolism, low concentration and high brain fogginess from the waking-up activity (it's actually as tiring as any other activity) and increaed REM phase, blood pooling from maintaning the same position for so many hours. Also try to eat something to recover after exercise, even if it's just 1 knees bend, try to eat a piece of fruit or anything afterward to take advantage of the post exercize recovering window. Even healthy people, if they don't after exercising, recover more slowly and feel more post-workout pain. This is the main feature of CFS. You accumulate "exhaustation" and you feel it the next day, when you push too much you might need days or week before you are even able to leave the bedroom, but it's always the next day. Which is bad because we have no signals that we're doing too much.