1. Jog through water. It's one of the most strenuous activities you can perform, since water is about 12 to 15 times as resistant as air. Running at your hardest, you can burn about 17 calories per minuteat least twice as much as you would burn running on pavement.
2. Start fast. Researchers at the College of New Jersey found that after a short warm-up, cyclists who punched up the intensity during the first half of their workouts and then cruised for the second half burned about 10 percent more calories than those who started slow and finished fast.
3. Warm up before you lift. A short spin on a bike or jog on a treadmill (enough to get your heart rate up) warms your muscles and tendons and gets fluids flowing in the joints; this increases your muscles' elasticity, allowing you to handle heavier weights and endure a longer workout.
4. Sign up for hip-hop. Surprising your body with a new dance or sport forces it to work harder because it's doing unfamiliar movements and using muscle groups in different ways. In the process, you'll burn more calories than you would by doing the same old routine.
5. Work out in the a.m. Research has shown that people who exercise in the morning keep their metabolism elevated for hours and thus get a jump on burning calories. Studies also show that people who start each day with a workout tend to stick with their programs longer.
6. Fuel up first. Grab a banana before you hit the gym, and it may actually help you slice off more calories in the long run. Shoot for 100 to 200 calories to nibble on: Yogurt, a piece of fruit, peanut butter and crackers, or half an energy bar are all excellent choices.