I will disagre a tad. One must have the attitude and conviction that one can use deadly force to prevent grievous bodily harm.
I have seen in training, two folks come to gun point with sims and one just freeze. The other shot. I have also seen a martial artist (or so he said) be unable to confront an attacker. On the surface, he had the right mind set.
However, well known biological/psychological processes can generate a freeze even in the well intentioned. Significant training and realistic simulations can help control this tendency.
Now you might say that freezing is attitude but I think it is more complex than that. You can avoid the freeze by developing automaticity of coherent emergency responses.