I think it's about choice - true choice. I believe the term is "ego strength".

Self respect, I think, is when you do not have to necessarily react when someone is treating you like a doormat. You've got nothing to prove, so it's okay. Not like "It's okay because I deserve it" but "it's okay because I can chose what to allow and what not to allow and I can not allow it in a rational, non-angry or non-aggressive manner".

It's peace with yourself.