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How to optimize calorie burn

Aim for 4 mph for a very brisk pace and 3 mph for a moderate one, according to the American College of Sports Medicine. Sing aloud while you walk—if you can belt out the chorus to your favorite song with ease, you need to speed things up. Pick a plan, then do two sets of each move whenever the right "prop" presents itself (or at the end of your walk). Do five sessions a week and you'll not only get double the burn of a so-so stroll, but you'll firm up all over in just two weeks—no running required.

Next: Tone up in town: The walk