Grab a pair of dumbbells and kneel on the floor with your hands below your shoulders, palms facing in, and your knees below your hips. Raise your left arm straight out to the side (your arms should be slightly bent). Focus on squeezing your left shoulder blade in closer to your spine. Hold for 1 count, then slowly lower to the starting position. That's one rep. Complete 15 reps with your left arm, and then switch to your right arm.