I'm not sure what ME/CFS is. Could you elaborate? I know it's hard to feel like you don't have control in your life. But you must fight the battle, or depression can swallow you up. Moving around as best as you can is helpful, as it produces endorphins, which give you a sense of well being and serenity. As I say, I don't know what your condition is, but there are exercises one can do in a chair or flat on your back, even in bed. Don't give up! And know that you can find support here.
Are you in the UK? I used to live in Abergavenny Wales, but am an American living in Illinois now (my home state)