When it comes to abs workouts, there are always the basics: planks and situps. This series is here to make those basics harder and then some. Tack this routine on to any workout and you'll feel a serious abs burn that targets your lower, upper, mid, and side abs. There's also a bonus: These moves will give your butt a workout, too. Do each move for 30 seconds with no rest in between. Then repeat up to five times and see how much you can handle.