seconding jiro's pushup idea.

on weekends, i usually just hammer out twenty-five pushups every two hours or so. during weekdays, I regularly kill myself with <a href=http://www.webmd.com/fitness-exercise/features/the-300-workout-can-you-handle-it>this</a>. floor wipers are pretty awful and by the end of it i can't do my second set of pullups. i know i'll get there eventually though.