This is an interesting question.  I hope some seasoned Friends will weigh in on this.  I may be borrowing from a Buddhist view here, but I believe in a middle path - everything in moderation.  I think there is a place for Jesus's teaching to turn the other cheek, but also we are made in God's image and not called to mortify ourselves but rather be grateful for our existence.  I think self-defense warrants consideration.  Mr. Miyagi's words from The Karate Kid come to mind -

Daniel: Yeah, but you like karate.
Miyagi: So?
Daniel: So, karate's fighting. You train to fight.
Miyagi: That what you think?
Daniel: [pondering] No.
Miyagi: Then why train?
Daniel: [thinks] So I won't have to fight.
Miyagi: [laughs] Miyagi have hope for you.

....But if push comes to shove...