Stand with your head facing forward and your chest held up and out.
Step onto balance disk with your feet shoulder-width apart or slightly wider.
Extend your hands straight out in front of you to help keep your balance.
If you wish to add an arm curl, place two dumbbells into each hand.
Sit back and down like you’re sitting into an imaginary chair.
Keep your head facing forward as your upper body slightly bends forward.
Rather than allowing your back to round, let your lower back arch slightly as you descend.
If adding an arm curl, bend the arms at elbows.
Lower down so your thighs are as parallel to the floor as possible, with your knees over your ankles.
Press your weight back into your heels.
Keep your body tight, and push through your heels to bring yourself back to the starting position.
If you added the arm curl, lengthen the arms as you stand.