For Eye-Hond Infinity coordination exercise Prof. Ilchi Lee writes that Raise your thumb (pointing upward) to eye level, holding it at a point in between your eyes and away from your face. Gently bend your elbow so that your arm is not stiff. Trace, in the air, the shape of the infinity sign (a figure eight) with your thumb. Move slowly and deliberately, with full concentration on the movement of your thumb. Hold your head still and follow your thumb with just your eyes. Repeat at least three times. Repeat with your other hand.
You can use both hands. Clasp your hands together with your thumbs crossing on top. Focus on the intersection of your thumbs and trace the shape of the infinity sign.
If you work at a desk for a long time and often feel shoulder and neck stiffness, this is a good exercise to relieve some of the tension and will also help during learning about Dahn Hak.