I know it sounds silly but the other day I switched up the way I count when doing reps and it totally changed my workout. Instead of counting each rep (1, 2, 3, 4, 5) . . . I counted backwards like they do before the space shuttle launches – 5, 4, 3, 2, 1. I know this may not seem like rocket science, but for someone that goes to the gym almost every day, anything to switch things up is a welcome change in my book.
If you like this idea you might like the idea of reversing your run.