https://www.t-nation.com/training/tip-hone-your-technique-with-wall-squats
Stand facing a wall with your nose and toes against it. Your feet should be slightly wider than shoulder width with your feet angled out very slightly.
Squat down as far as possible with your arms hanging between your legs. (I prefer this to the variation where the arms are kept high.) With each rep, you should be able to drop a little farther.
Perform 3 sets of 15 reps every day until you can drop your hips below your knees.
https://www.t-nation.com/training/tip-do-a-deep-bodyweight-squat-daily
Do it at least once every day, with bodyweight, for 30 seconds.
https://www.t-nation.com/training/tip-make-the-face-pull-a-staple-exercise
https://www.t-nation.com/training/tip-do-the-back-bridge
- Lie on your back and put your hands beside your head.
- Push up off your feet and push your chest back at the same time. Rest on your forehead (or as close as you can get).
- Now rock back and forth, decreasing the distance between your legs and head.
- Keep your body really tight and flex every muscle from your chest, neck, back, all the way to your legs and feet.
https://www.bodybuilding.com/exercises/bottoms-up
https://www.t-nation.com/training/tip-do-the-lateral-shuttle-run