HOW: Get set-up balancing on one foot on an elevated surface. Begin the exercise by reaching forward with the foot that is in the air and letting your hip and knee bend with your knee moving forward over your foot. Just tap the ground if you can, then return to starting position, then reach backwards with the leg in the air and perform a posterior lunge going as deep as you can with good form. Return to starting position and repeat.
FEEL: You will feel your quads and calves working when you reach forward vs. your glutes and quads more when you perform the posterior lunge. However, your entire leg will be getting a workout.
COMPENSATION: Do not put all of your weight down on the ground with the leg you're reaching with when you reach forward, just think of tapping an eggshell. Try to keep most of your weight on the front leg with the posterior lunge. Focus on good torso and knee position the entire time, do not let your knee cave in/out, keep your pelvis level to the ground, maintain good balance.
