Teaching beginners, you have to break down a lot of conditioning. Years and decades of being told not to be rude. Don’t swear, don’t spit, don’t use nasty words and don’t touch people inappropriately. Almost everything that falls under the umbrella of self-defense is rude. Injuring people is very inappropriate physical contact. Setting boundaries is yelling at strangers. "How can you hit someone if you can’t even look him in the eye?"