Some days I can do my run and come back and feel like I could run it all over again. Other days I run and feel like it is a struggle to get through.
Am I burning more calories on the days the runs don’t feel as fluid than on the days I’m feeling strong?
How about lifting weights? Some days I can do my reps without too much trouble, other days I can’t get through all the reps. Am I building more muscle on the days I do fewer reps but work my muscles to fatigue?