Find a flat, tall, sturdy surface you can stand against, such as a door or an empty wall.
Stand with your back, head, and arms against the wall. Step your feet slightly closer than hip-width apart, and bend your elbows to form a 90-degree angle.
Slowly move your arms overhead, sliding them against the wall and gradually straightening them. Keep your arms, head, and back pressed against the wall the whole time.
Slide your arms back down the wall until they're bent at a 90-degree angle in your starting position.
This counts as one rep. Repeat for one set of 10 reps.