PNF resisted arm elevation in sitting ("PNF D1 UE" Shoulder strengthening with band, in sitting; 01)

Sit up straight in a chair.
Hold the ends of an exercise band in each hand with your arms relaxed on your knees.
Grip the band tightly with the arm you don't want to move.
With your other hand, gradually pull the band diagonally up and away from your body.
Your arm should finish diagonally up and away from your side with the palm facing forward.
Make sure the movement is controlled as you bring your arm back to the starting position.