Wrap a band around a power rack or pole at shoulder-level and stand upright with your feet shoulder-width apart, facing a direction perpendicular to the band.
With the arm closest to the band held at shoulder-level and bent, grip the band.
Exhale and press diagonally forward and inward across your body while keeping your arm at shoulder-level, not allowing its height to change or your torso to rotate.
Continue to press your arm diagonally until it is fully extended.
Inhale and allow your arm to bend back to the starting position, continuing to prevent your torso from rotating.
After all reps are completed, switch sides and repeat the movement. 10 reps prescribed means you should perform 10 reps on each side (20 total).