Why does pushing and/or pulling on the head of a horse create stress for this animal?  Horses are prey animals and in the wild, they are fair game to meat eating predators that tend to strike in the vulnerable throat area. So in horse language, a push or a pull on the head area sends a predator type message.  The question then arises, how should a person be, move, when working around the head of the horse?  One uses what is called a drawing position with our body when we are at the horses head/neck area.  This position is accomplished by simply folding our core (belly) backward slightly.  Try the following exercise. 

Stand up straight with good posture; now bend over slightly as if to bow to someone.  Notice when you bow, your core and hips draw back slightly.  Now stand up straight again and this time draw your core and hips backward slightly without bowing with the head and shoulders.  This is the drawing or inviting position. When facing your horse’s head, try this drawing position, inviting the horse to come toward you with his head.  You can even walk backwards a few steps as you draw with your core.  Your horse will love you for this!  You will no longer be sending a predator message to his head!  In other words, you will no longer be “in his face”.