Well, it's not easy but what I do is ignore the whining Slump Monster in my head. I get dressed, strap on my shoes, and go for my walk (3.5 miles). I always feel better after that, every time. When I MUST clean house (a chore I hate), I just force myself to get going. Once I get going, then I feel like continuing. If it helps to turn on music, then I do that. I might sing while I do it (I live alone so no one gets hurt when I do this, LOL).
Make sure you're getting all your vitamins and getting enough sleep at night. If all those things are good, then sometimes you might just have to get tough with yourself and not listen to that voice that says, "Let's lay down and watch Regis and Kelly!"
One dancer for each 5 lbs lost!