Squatting facing a wall with arms extended provides feedback to teach an upright squat and develop mobility for a deep squat.

“assume your normal squat stands and I'm talking about a narrower stands you know shoulder wi or somewhere there and approach the wall face the wall put your arms out and start squatting and you will find the wall is going to teach you so it is the feedback from the wall if you start doing something funny with your spine you're going to hit your head on the wall and fall back so it's it provides terrific feedback”