Likely seeing how closed minded and prejudiced people can be keeps this trait alive, as I don’t want to become them. The theory of Ego applies best in this case. My ego keeps me calm and mature which has the effect of keeping my mind open.
The adult in me won’t allow me to act childish and be closed minded. It also allows me to see solutions to problems that I might not see otherwise. That is how my second good trait is Open-Mindedness and how it works for me.