There are so many exercises out there, and there's so little time to try them. That's why combinations are important. Combo lifts, in which you group two or more separate moves together into one super-exercise, can work just as much muscle as several separate exercises-and they do it in considerably less time. Take this combo from Anthony Fazzino, C.P.T., a trainer at Gold's Gym in downtown Manhattan, which provides a full-body workout in just four steps.
HOW TO DO IT
Stand holding a light dumbbell in each hand  and step forward into a lunge with your left leg (lower your body until your right knee nearly touches the floor) . Return to the starting position, simultaneously curling the dumbbells until you're standing with both elbows fully bent . Now rotate your arms away from your sides so that you go into the bottom position of a shoulder press, and then press the dumbbells overhead . That's one rep. Perform 12 reps, then switch legs and repeat-that's one set. Perform three sets, resting 90 seconds between each. Even though you'll be working with light weights (you'll have to, as the exercise requires too much coordination and stability to be done heavy), "the lunge and curl to press will demand a lot of muscle work from your core, legs, and upper body," says Fazzino-providing an effective fat-burning and muscle-building workout all on its own, in under 10 minutes.