Principles at work
One of the things that I like to use (I think of it as a principle) is the range of effectiveness. One of my favortie quotes of O'Sensei (paraphrasing) is that no matter how strong someone is, once they are outside of their sphere of strength they are weak. I work in Law Enforcement so most of the time the people I have to deal with physically are bigger than me. Even in conversation if you can overextend them you can lead them and talk them out of wanting to fight/argue.
And this is especially true when it comes to physically defending yourself.