Circuit training routines can be created with free weights, machines, kettlebells, cables, you name it. They're extremely effective for fat-burning and increasing cardiovascular and muscular endurance. Sounds good, right? Naudi Aguilar of FunctionalPatterns.com hooked it up with a fast-faced circuit, and to spice it up, using multiple pieces of equipment that most people can find at any gym or even in their own home.