This exercise is a wonderful exercise to build hip flexor strength to help walking, stair climbing, even back stabilization. Start in a standing position, core engaged. The leg that you stand on will get a great stabilization workout if you keep your hip under you. Don't let it drop to the side. You are going to lift your knee into a march or high knee in front of you. Great for your hip flexor strength. Do not lean. Do not hike your hip. Slow and controlled. Add Ankle Weights or Exercise Bands for more of a challenge.