[esad]

Address the ball as normal. Take your right leg and lift it off the ground. Point your toes of your right leg down and then lightly set your toes on the ground a foot or so behind you.

Now make a normal swing. You might fall over or at the least you'll have trouble. It will teach you to keep the upper body from moving forward and back so much and will force you to maintain balance through the swing or you'll fall over. You can see the first pic that you are lifting the foot of the left leg which means that at the top of your backswing there is almost no weight on that leg. It most likely makes you rock your swing.

FWIW, Nicklaus rolled his left ankles over and he tried to do it. It's not necessarily a bad thing.