The doctors say you should exercise because that is good advice across the board. The human animal was not designed to be idle, and these days they are even saying that a sedentary lifestyle can be as bad for you as smoking. You have to keep your body moving no matter what, and as a person gets older it's even more important.
The thing is, if you have FMS you have to be incredibly persistent, in finding out what you can do and how much and what works for you. this is very challenging and it can lead down paths to feelings of despair because it turns out you can't do a certain kind of exercise after all. I know, been there done that and probably not finished with going there and doing that. But it's very important not to give up.
There are dozens of different kinds of exercise you can do at home, or just in your yard or park or whatever. Walking is one of the best. Don't overdo it and have a set back, but don't give up on exercise.
I found the most important thing, after making sure I get enough sleep and good food, is to really listen to my body. If you literally ask your body what it can do today, it will tell you. I don't force it, but I make myself at the very least go for a walk every day. I have dogs, so that makes it necessary anyway....they are great motivators!
The other thing is, put on music and just move. You don't even have to dance, as such. Even lie down on the floor and move! Sit in a chair and move, just move to the music.
Just move in whatever way you can for that specific day, and that is your exercise. If you do this, and are very persistent with it, you will find your body will get stronger and be able to do more. It may happen so slowly and gradually that you won't think it is happening, but it is.
James 192, it is true that you can force your body into starvation mode if you exercise a lot and don't eat. But, exercising makes your body want to eat, so as long as you are not determined to starve you won't. Just eat good healthy food and exercise and listen to your body.