basically, kneel with a swiss ball to your side, but not touching your body at all. Keep your back straight, and your stomach tight and pulled in. Rest your forearm on the edge of the ball, then lean to that side so you're leaning on your forearm, on the ball. Your body should remain straight, and it is a slight movement, the opposite leg /knee can come slightly off the ground. Hold position for 30 seconds and repeat 3 times on each side. Activates core stabilisers.