Want to kickstart your body's calorie-burning furnace? There are a few surprising ways to do it. If you're a walker, then get your arms involved. You can burn up to 15 percent more calories by bending elbows at a 90-degree angle and pumping your arms in concert with your walk. Keep elbows in and the movement controlled.

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In these last dog days of summer, quench your thirst with cold water before you work out. A British study found that exercisers who drank cold water before a hot-weather workout worked out longer and said their workout felt easier. Cold water will also help keep your body temperature down, so refrigerate that bottle of water or fill up your container with a pitcher kept in the fridge. When using dumbbells, don't worry about the number of reps you can do - worry about how much weight you're using. Exercisers who increase the amount of weight they use burn more calories at rest than those who do more reps with lighter weights.