answer:I get the same thing with anything that makes me do work. I was that way with going to school, and I’m that way with going to work, and I’m that way with walking. I think the physical exercise is different than the first two I mentioned though. Anything can change the way you physically feel. Our bodies react to things we do to them more than you would think. It could be just tiredness, or it could be that you ate more wheat or dairy on those days, or it could just be an attitude thing.