A very simple two people drill. One person stands and can only move his arms straight from the shoulder at a slow pace. Person number two needs to touch his body to the standing person body while avoiding getting touched by the moving straight arms. Consider each arm to be a knife and remember one touch means a cut or a stab. Work this drill slowly as you relax your eyes to see both the person and all the nice empty space around him or her. Learn how your body can get the job done or not and learn to avoid running ahead into the knife thinking you can wing it along the way.
Avoid pushing or pulling on the arms at all and every touch is considered an injury during the drill. Learn to be patient in your movement and keep the main goal of survival and living well in mind instead of having a short term goal of winning a game.
Keep your face relaxed and your eyes from falling into following the movement. Keep breathing and moving and learn to avoid bending in place to avoid a hand coming your way when the other arm is doing the same.
Simple is good never easy.
The Martial Art of Walking 