Towel Stretch

Grasp a three‑foot towel behind your back with one hand and hold the opposite end with the other hand.
Use your good arm to pull the affected arm upward to stretch it.
Repeat 10–20 times per day. For an advanced version, drape the towel over your good shoulder and grasp the bottom of the towel with the affected arm, pulling it toward the lower back with the unaffected arm.