Start in first position, facing your chair/support, with your heels together and your feet open in a "V" shape. Rise up so that you're balancing on your tippy toes with a slight bend in your knees.
Step your right foot back about one foot. Lift your right leg up as close to hip height as you can get while maintaining a braced core. You shouldn't feel pain in your right hip. If you do, lower your leg down to a height where you no longer feel pain. Make sure to maintain a neutral spine and avoid arching your back. If needed, your standing foot can be flat.
Once you've lifted your leg as high as you can while maintaining proper form, lower your leg back to the ground, stepping the foot behind your standing leg so you're in a narrow lunge. You should have a slight bend at the knee in both legs throughout the entire movement.