Hmmmm, you know, I usually work out about 2hrs just about every day. One day I got a phone call and had to leave the gym early, I think I was there 30-40 minutes. I felt so unfinished afterwards and noticed I got so much more tired throughout the day. I think for me, exercise is an outlet for my stress and if I don't have my 2hours in, my body wears down easier. Maybe I'm just weird, but I like to exercise. I feel so much better after I do.