A plank is a low impact exercise that is a serious core burner. Holding in the plank position engages multiple muscles at once which not only makes your torso stronger but can help you lose belly fat. Best news - it's one of the easiest moves to accomplish all by yourself at-home. Plus, it never gets old. Once you've easily achieved the position, keep challenging yourself. Start with 15 seconds, then increase to 30, 60 and so on. 74 year-old Cher says she can plank for 5 minutes!