Stand back-to-back, pressing shoulder blades together, knees shoulder-width apart. Walk your feet out a foot, so that you are supporting one another with your upper bodies. Slowly bend your knees, lowering your tailbones down to the ground as you squat as low as you can go without your knees moving forward past your toes. Hold the squat position for as long as you can—start with 10 seconds, then build up to 30 seconds. Pressing against one another, straighten legs back to standing.