Put all of your weight into your standing leg and step backward with your other foot into a lunge position. Your front knee should be bent and in line with your big toe. You can lead with either foot.
Stay in a high lunge with your arms raised overhead.
Shift your weight into your front foot and bring your back leg up into your chest so you are hugging your knee, balancing on your standing leg.
Gently put your back leg down and return to the high lunge position.
Repeat these knee lifts for 30 seconds, then switch sides.