Start on your hands and knees with your hands under your shoulders and knees under your hips.
Your back should be level with your neck and head in line.
Start by arching your back up towards the ceiling.
Tuck your tail bone down, round your shoulders and drop your head down.
Next, reverse the movement.
Lift your head up to look ahead of you.
Dish your back, and push your tail bone up towards the ceiling.
Repeat the movement.
Keep your arms straight throughout this exercise.