Standing Bus Drivers
Take hold of suitable weight plate, keep your core tight, your torso straight and stand with your feet flat on the floor.
Grip the plate at the sides at '3 and 9 o'clock' so palms face inward. The arms are extended out in front of you. This is the starting position.
From this position, rotate the plate one way as if it were a steering wheel. Once you reach maximum rotation one side, oppose the movement to the opposite side.