I vote for starting w/mild exercise, gradually increasing, always practicing moderation. Not overdoing. More ... walk around the block stuff than going gungho at the gym.
Many CFS types seem to have some sort of virus ... bug ... parasite ... whatever infection or reaction to past infection, and I think that exercise does help to normalize the immune system.
My DD had postviral CFS & found she had flares after exertion ... too much exercise (a relative term) might be stressful on the body & more hurtful than helpful in the long run. She did find that regular, mild exercise was beneficial to sleep & well-being, but YMMV.
There are mixed messages over this for CFS. My personal opinion is that forcing yourself to exercise is a bad idea. But... if you don't do any exercise, your body will start to get weaker and more tired. Like elmhar says, mild exercise would be beneficial - a good steady 20 minute walk or something. Nothing too tough or pushing yourself to hard. It is hard to get motivated to start with, especially if you don't feel you can get up out of a chair. But mild exercise for short periods of time can't harm at all.
Listen to your body! If you excersize and really pay for it days afterward, it is a bad thing. Decrease to a tolerable level, or you may be building up nitric oxide. Literally you are oxidizing your body by doing so. Advancing aging so-to-speak. There is much scientific stuff out there and getting more in regarding CFS. Its not a medical mystery, or unknown fatigue that is slapped on people because they know nothing. Then again,you may not have true CFS, and excersizse may benefit you. IF you totally understand the words, 'excersize intolerance" in cfs, then definitley DO NOT push yourself.
Then again,you may not have true CFS, and excersizse may benefit you.
Exercise is of benefit to everyone. To suggest that if you have "true CFS" (whatever that is because as far as I was aware there still is no definitive test for it - a lot of it is still a "medical mystery") exercise is of no benefit is completely wrong. If you stop exercising, stop working, stop everything because of CFS, you will get weaker and feel like doing even less. It's a case of balance - not pushing yourself too far but not stopping yourself from doing everything. Neither will be of benefit in the long run.
It has been 15 years since I had it, but I can still remember having to force myself up off the couch to exercise. And, for the longest time it seemed, pushing myself up off the couch was the full extent to which I COULD exercise. Back then I was told not to push myself... to do only what I could comfortably tolerate. I think sometimes the mental fatigue was worse than the physical fatigue and, once I pushed past that, I could tolerate more than I thought I could. I found that setting the treadmill in front of the TV helped... at least during the winter months. If I could distract myself while walking, I could get a little more time in before I ran out of steam.
Best rule of thumb is to take it easy, but you have got to get moving, even a little. Strive for 30 minutes each day, even if you have to break that up into 3 or 4 sessions to get it all done. Walking is good, but if you can't manage that, try a peddler. If that's too much, try some gentle stretching, then work up to a few strengthening and stablization exercises. Eventually, you will be able to do more. Increase as you can, but gradually.
If you don't move, your muscles will atrophy, including your heart and lungs. You will gain weight and that will cause you more fatigue as you have to move more of yourself around with less muscle tone to do so, not to mention again your heart and lungs trying to keep up with a growing you and nothing to help them out.
If you can, try water therapy. The water makes you boyant so you're not lifting so much of your body weight, plus it gives you some resistance when you move. A heated pool will do wonders for your aching body, too. Just be sure to drink lots of water when you get out.