During crowded times at the gym -- say, around beach season -- it's harder to find an unused piece of equipment than it is to hail a cab at 5 o'clock on a rainy Friday in New York. No worries. You can get a great full-body workout by using something that every gym has plenty of -- weight plates. Claim a bench and a few plates of different weights, and you'll have all the equipment you need to do this circuit.