Stand in a staggered stance with one foot in front and your chest tall. Bring your fists up by your chin and your elbows against your ribs.
Rotate at your hips and keep your core tight as you punch one fist upward followed by the other.
Lower your body and roll to one side, pivoting on your feet and keeping your chest up as you do. Come to standing. Imagine you're ducking slightly under something.
With the same foot in front, lower your body and duck back to the other side, pivoting on your feet and keeping your chest up as you do. Come to standing.