Standing sideways against a wall with elbow bent and in at side.
Press the back of wrist into the wall whilst squeezing elbow in towards body.
Press at a comfortable resistance (~20% resistance to start). Make sure your arm does not move.
Relax your head and shoulders and hold for 10-20 seconds.
Release and repeat 2-4 times on each side.
Repeat 2-4 times a day especially before activity and after periods of inactivity.