Here is Friday Fast Fitness - Quick shoulder and triceps stretch, without adding new bad positioning. Use this instead of the usual stretch of pulling elbow overhead with the other hand, which usually results in leaning the head forward and arching the lower back.

Instead:
- Stand diagonally in front of a wall.
- Raise elbow (the one closest to the wall). Lean arm, armpit, and body against the wall
- Breathe. Relax. Smile. Switch sides.
Do not arch the lower back or tighten any part, or it will hurt and not be right or healthy. That would be silly.