I felt the same way earlier today. My brother came in my room around 5pm and said, ya ready to go to the track? I was like, nah I don't feel like it today. My stomach's been bothering me. I went to the bathroom and felt better, lol. So I went and worked my fat *** off, haha. I think I overdid it though. I feel very worn out now and my legs are dead. I'm glad I went though. I just have to go slow. Having a cheat day, or a day of rest without exercise is not a big deal at all. If you think of weight loss more as a lifestyle, not just a short term thing, then you have to listen to your body and rest when you need to. So don't feel too bad about it.