Start resting on all fours with a dumbbell on the left side of your body.
With your palms flat, rise up off your knees onto your toes into a high plank position. Your legs should be straight. The wider your feet are apart, the more stability you'll have while doing the exercise.
Squeeze your glutes, keep your hands directly underneath your shoulders, and contract your abs (keeping your belly button pulled in) to prevent your butt from sticking up.
With your head and spine in line, look about one inch out in front of you. Don't tuck your chin.
Maintaining this form, grab the dumbbell with your right hand and pull it underneath your body until it's on your right side. Be sure not to rotate your hips.
With control, grab the dumbbell with your left hand and pull it underneath your body until it's back on your left side.