If you are close to a warm pool, that would be a great way to start exercising. I can't tell you how a big of difference diet and exercise make. It won't cure you, but it'll help.

I keep telling myself I need to start walking again, even if it's only a block a day to start, and I've been procrastinating... Going outside means getting dressed and putting on decent walking shoes, etc.

Since you're a fellow vampire, you should probably be taking Vit D. A few people had suggestions on specific types in my thread here: http://neurotalk.psychcentral.com/thread222011.html