This touched on one of the things that impressed me about CK in that if he makes a mistake it doesn't get him down and he makes up for it.
You don't want your QB to be overconfident or cocky but you do want your QB to have ice water in his veins and a short memory and not let a mistake faze or shake him.
You make a mistake you come out even better next time. Mistakes should drive you to be determined to be better and stronger and not tear you down.