Fit-ball Overhead Squat
Step 1 Stand tall with your weight in your heels and chest up. Hold your gym ball over your head, with your arms completely straight.
Step 2 Keeping your chest up, push your hips back and descend into a full squat. Keep your arms as high as you can.
Step 3 Still keeping your chest up, drive through your heels and stand tall, squeezing your glutes.