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.
Get down on all fours with your knees placed directly below your hips and palms placed directly below your shoulders. Now, raise your right arm forward and stretch your left leg backward at the same time. Create a tension in your back by flexing your foot. Hold the position for a few seconds and then come back to the starting position. Repeat the same using your left arm and right leg. Repeat 15 to 20 times on both sides.