Kneel with the ball in front of you and lean into the ball as you place your forearms on it. You should already feel your abs working here, so be sure to pull your navel toward your spine.
Push your arms into the ball as you roll it away as far as you can without compromising your form — breaking at the waist or over-arching your back. Hold this plank-like position for two to three seconds.
Slowly return to the starting position by contracting your abs and rolling the ball back toward your knees.