Start on the floor, resting on your forearms and knees, and come up into a plank position. Contract your abs to prevent your booty from sticking up or sinking. Your spine should be parallel to the floor, your abs pulling toward the ceiling, and your feet should be close to hip-distance apart.
Once you're in a strong elbow plank, step your left foot outward (about eight to 10 inches), keeping your core engaged and strong. Step your left foot back to the starting position. Now, step your right foot outward before coming back to center. This counts as one rep.