There are days that you don't want to work out. Or there is something you want to eat you shouldn't. But then there are the days when it isn't that, it just really is a hard day! You do the workout, but no matter how hard you work, the results aren't quite up to normal. You just can't get the muscles and the brain and the lungs all working together.
What do YOU do on those days? I have learned to listen to my body. Sometimes these days are my body telling me to take a day off. Time for an extra rest day. Keeping in mind this doesn't turn into a rest week, month, etc. That is ok and a good thing to do when appropriate.
Sometimes, it just is a day that is harder than others and the very best thing I can do is do it anyway. I feel great at the end because I did it even when I didn't want to. When 10 pounds FELT like 40. When my brain wanted to know why I was even bothering. Those are the days I really NEED to do it for me. Not for the physical, but for the mental exercise. Those are the days that once done, fuel me the next time it is a hard day, and I know there is another one around the corner someplace.