Stand with your feet together and your chest tall, fists up by your chin and your elbows against your ribs.
Take a controlled lunge (or large step) backward with your right foot. As you lunge back with your right foot, drive your right arm forward into a punch to meet the boxing bag. Keep your other hand by your face.
Your knees should be bent at 90-degree angles. Your left knee should be positioned directly over your ankle, and your right heel should be lifted.
Keep your core tight to maintain your balance, and press your front heel into the floor as you push back up to the starting position.
Alternate on the other side, lunging back with your left foot and punching with your left arm before coming back to the starting position.