Stand up straight with a clear path in front of you.
Imagine a straight line on the floor extending away from you, or place a straight line of tape along the floor.
Keep your eyes focused on an object within your eye line and nod your head up and down.
Walk along the line on the floor as if you are walking a tightrope whilst continuing to nod your head.
Your eyes should not move from the object.
As you feel more confident, increase the speed of your head nodding.