Sally, I think I know what you mean. I feel the same sometimes. And my physical condition definitely plays a big part of how I feel mentally. When I don't feel "good" everything else is compromised. One day I feel pretty good and stuff doesn't bother me too much and then the next day I feel yucky and everything seems hopeless.
My life is pretty boring, too. At least compared to how it used to be. But.....my idea of excitement and fun has changed so much over the past 10 years that I'm not sure I could enjoy my "pre-MS" life right now. This stupid disease makes me feel much older than I really am.
I guess I don't have any solutions to offer you....just an understanding shoulder.