Sit upright on a firm chair, or surface, with your feet hip width apart.
Sit close to the front of your chair, so that you are not leaning on the back of the chair.
Lean your weight onto one side of your pelvis, and lift the opposite side of your pelvis slightly off the chair.
Place the lifted side slightly backwards as if walking your bottom toward the back of the chair.
Repeat this with the other side until you are right back in the chair.
Once at the back of the chair, complete the same movements in a forward motion to move toward the front of the chair.
Aim to keep your body upright at your shoulders, rather than leaning over.