Here is a video showing you the single leg box squat. This is a great exercise to help you develop better balance and build glute and quad strength needed for running. Start this exercise using body weight only and as tall of a box as you need to complete with good form. Focus on pressing through your heel when standing and using a controlled motion when sitting. Progress to a lower box and add weight and repetitions as you improve. As always, let me know if you have any questions on how to perform this valuable exercise.