Boxing is about respect. Getting it for yourself, and taking it away from the other guy.
She grew up knowing one thing: she was trash.
To make a fighter you gotta strip them down to bare wood: you can't just tell 'em to forget everything you know if you gotta make 'em forget even their bones... make 'em so tired they only listen to you, only hear your voice, only do what you say and nothing else... show 'em how to keep their balance and take it away from the other guy... how to generate momentum off their right toe and how to flex your knees when you fire a jab... how to fight backin' up so that the other guy doesn't want to come after you. Then you gotta show 'em all over again. Over and over and over... till they think they're born that way.
The body knows what fighters don't: how to protect itself. A neck can only twist so far. Twist it just a hair more and the body says, "Hey, I'll take it from here because you obviously don't know what you're doing... Lie down now, rest, and we'll talk about this when you regain your senses." It's called the knockout mechanism.