Harrison is also a hardcore burpee devotee. "It's a full-body exercise that will get your heart rate up, and it can be progressed and regressed in a variety of ways," she explains. (Psst—here are nine ways to do a burpee, no matter what your level is.) But her go-to burpee has a twist: "I also really love mountain climbers for some of the same reasons, so why not combine them?" The combo of the two will skyrocket your heart rate for a major cardio challenge.

Maybe you exercise to tone your thighs, build your biceps, or flatten your belly. Or maybe you work out to ward off the big killers like heart disease, diabetes, and cancer. But how about sweating to improve your mind? "Exercise is the single best thing you can do for your brain in terms of mood, memory, and learning," says Harvard Medical School psychiatrist John Ratey, author of the book, Spark: The Revolutionary New Science of Exercise and the Brain. "Even 10 minutes of activity changes your brain." If you need a little extra incentive to lace up those sneakers, here are five ways that exercise can boost your brainpower.
3. Practice “glycogen depletion” and repletion. Once you get the hang of eating as described in rule #1, you have to start manipulating your carbohydrate intake. The key is to keep it simple: on days you don’t workout reduce carbohydrate intake, on days you do workout increase it. Doing this is like applying a blow torch to your arm fat. Just make sure you don’t go into ketosis a la Atkins—research has shown that total carbohydrate elimination is NOT necessary for maximum toning. Not to mention, the acidic breath you get from ketosis stinks!
Protein and fat loss go hand in hand. This nutrient supports muscle growth and raises your metabolism, making it easier to slim down. It also promotes satiety and reduces hunger, so you'll eat less without even realizing it. The American Journal of Clinical Nutrition states that high-protein diets can positively impact appetite, cardiometabolic risk factors, body weight and other factors.