At first glance, this workout looks simple: An upper-body workout using a band. And yes, this do-anywhere plan does hit all your major upper-body muscles in a circuit format. But even though your upper half is hard at work, your lower body does not get a reprieve: For each move, you’ll assume a challenging stance or position and hold it for the duration of each exercise to improve balance, stability and core strength, amp calorie burn, and leave your legs shaking and quaking.