As my grandmother used to say, I got up on the wrong side of the bed this morning. I had slept for 7 hours but for some reason didn't feel rested and I was just in a bad, pessimistic mood. I had made all kinds of plans for my Saturday but none of them appealed to me any more. I went to the health club as planned for an 8 am session with my personal trainer. About 10 minutes into the workout, I realized that I felt 100% better than I had when I first woke up. When I left the health club after the workout, I was happy and looking forward to the rest of my day.
For me, the main benefit of exercise is not what it does for my weight. The main benefit is what it does for my mood.