Stand with your feet in a horse riding stance, toes pointing straight in front of you, and your arms in front of you, palms facing each other.
Imagine there is a large piece of glass that is in front of your chest that you will be polishing.
Your hips rotate from side to side as your weight shifts, but your hands stay in front, polishing the glass.
Your arms and hands are making a circle.  Be careful not to pull your elbow back.  It is the turning of the trunk that moves your hands.