It was done through games, role playing, and clear expectations. Example--- we played the
robot game. Arms out, walk like
robot. You could not get any closer to someone than the robot arms (arms straight out or straight out to the side) or your machine went haywire. After playng this a bit (which is fun), he was asked to always put this into practice --- and I would give him that verbal cue. "Robot arms X(his name)" and he'd be mindful of not getting too close.