Active ankle inversion with ball (Ankle inversion strengthening, passing a ball, sitting)

Sit upright on a chair with both heels on the floor.
Place a small ball between your feet.
Keep your heels down on the floor at all times.
Turn one foot inwards to gently push the ball to the other foot.
Repeat with the other foot to pass it back to the original foot.
Continue to pass the ball back and forth between your feet.