I hate to exercise. It's tolerable if I have some entertainment, but then I have a hard time keeping track of my reps. I could use a mechanical tally keeper, but I prefer this app, which can keep track of reps while playing games or watching youtube. It floats on top in a little bubble off to the side and I can move it if it somehow gets in the way.
Its the little orange thing in the upper corner of the screen shot.