I totally agree with you about how inadequate the doctor's response was! Been there done that. But he's right in a way, just not in his approach.
One thing I read that I'll always remember is that "People with fibro/CFS can't afford NOT to exercise." But of course, we don't have the energy to even think about it.
The answer is to start VERRRRRRYYYYYY SLOWWWWWWWLY. At first I walked for 3 min, then 5, then 10, now a year later maybe i can do 25 min on a good day. But it HELPS, ohmigoodness, how it HELPS!! Can't feel the difference at first, until suddenly you look back and realize you're not getting such and such symptom any more or that now you can do X and you couldn't at first.
But it's like quitting smoking. You have to be ready to start your walking program and you have to really want to do it.
In addition, light strength building and stretching is important too. I have a link to a baby step plan you can do at home, which I'll post for you as soon as my fibro fog lifts and I remember where I put it so I wouldn't lose it!!!!!!!!!!!!!!!!!!!!!!!! ARGH!!!!!!!!!!