This move provides a unique challenge.
The legs are kept firmly together like in the military press, and then you shift the hips and bounce from one side of the mat to the other side keeping the hips straight. The upper body is stationary, your lower abdominal are engaged as you stabilize your pelvis.
You can start with 2 bounces each side and then reduce to one bounce each side.
Once this move is mastered challenge the balance further by holding the arms straight out in front of you, as though you were holding ski poles, and bounce from side to side.
Remember to keep those knees together and slightly bent!