Stand with your feet together. Take a controlled lunge (or large step) backward with your left foot.
As you lunge back with your left foot, drive your left arm forward to maintain your balance.
Lower your hips so that your right thigh (front leg) becomes parallel to the floor and your right knee is positioned directly over your ankle. Keep your left knee bent at a 90-degree angle and pointing toward the floor. Your left heel should be lifted.
From the ground, drive your left knee up, coming into a standing position with your left leg lifted at a 90-degree angle. Simultaneously drive your right arm up to maintain your balance.
If it's too hard to come into the knee drive from the lunge, step your left foot in to meet your right, then raise your left knee up.