Place the thick powerband around the shoulder so the band is on the outside edge of the shoulder joint (aim for the outside of the t-shirt seam line). This will mean the humerus will be glided back and the band won't cover the joint line. Have the band attached to a solid pole behind you. With the other theraband attached in front, step forward to get the tension on the thick band to create the posterior glide in the joint. Keep elbow just away from body, elbow at 90deg and shoulder blade pulled back and down. Pull the theraband laterally by rotating the arm outwards, pivoting at the elbow as an axis point (make sure the elbow stays bent at 90deg). Don't let the elbow move out of position or let the shoulder blade move.
Make sure the thick powerband is place correctly as to not block the joint, but be as close to the joint / head of the humerus as possible for best effect. Progress tot the 60 degree position