Inflate the ball according to the specific ball's instructions. Note that different balls have different air PSI requirements.
Place the ball where you want to sit. Slowly lower yourself into a sitting position so that your buttocks firmly rests on the top of the ball.
Keep your feet are flat on the ground and bend your knees at a 90-degree angle.
Straighten your back and pivot your hips until your hips are at the same 90-degree angle of your knees. You should be seated so that your back is straight with your hips 1 to 2 inches higher than the knees.
Stand up and move around about every 20 to 30 minutes as needed. Sit only for as long as you are comfortable. Over time, your body may become adjusted to using the chair as a seat, and it will become easier for you to sit for longer periods.