How much do you exercise?
And when do you do it? I just started to use the treadmill and I am doing about 20-30 minutes a night when I get home from work. I know that most people exercise in the morning, but evenings seem to work better for me. In the past I have always started out doing too much, too soon and ended up quiting. So I am now I'm trying the slow-and-gradual approach:-)