Successful violent criminals are really, really, really good at reading body language. If you're not absolutely committed to using the gun, if you're not willing to fire, the criminal will read that on your face and in your body and you will very likely have to shoot in order to save your own life. But if you are committed to action, the criminal will read that
This is the reason I don't advocate that everyone should have a CCW permit or even own a gun at all (for self defense purposes). I'm really into guns, however, my mom is not. She's asked me if I think she should have a gun for safety and I've told her absolutely not. While I fear how she would fair in a given violent encounter, I'm quite confident she wouldn't pull the trigger and would only make the situation worse if she even pulled out the gun to begin with. I'm sure I couldn't live with myself if I told her to get a gun and then it ended up being used on her instead.
Personally, the primary "mindset" should be avoiding/removing yourself from potential confrontations (like someone said, humility can be a huge de-escalator). However, if it comes down to me or them, I'm the one that plans to go home at the end of the day.