Stand straight with your legs a bit wider than your shoulders. Lift your arms on sides so they make 90 degree angle with your body.
Start by pointing your thumbs up and do a small arm lift the same direction as your thumbs are pointing to.
After doing required amount of repetitions, point your thumbs forward and push your arms a bit to the same direction as your thumbs are pointing to.
Continue to do the same as previously but changing your thumbs pointing direction to back and bottom.