A. Grab 1 heavy or 2 light dumbbells in your hands, and hold them behind your head. Elbows out to the side, chest open. Avoid straining your neck forward. Keep good posture and relax the shoulders.
B. Lower down into a squat, fighting to keep your chest facing forward. Sink as low as you can with the weight in the heels of your feet. Arms relaxed.
C. Raise up from the squat and press the dumbbell(s) overhead, extending through the triceps. Press them UP and not forward.
D. Lower your arms back to starting position and repeat with the squat.
Modifications: You don’t need dumbbells if you don’t have them: a water bottle or anything small & weighty will do. Reduce the range of motion to make this easier (don’t squat as low) and focus on using your triceps and core to protect your back.