What was your life motto?

Since I was a child I had this life motto.It was "Don't judge a book by it's cover".I always told myself that everybody has its own reason on how they act, they maybe an introvert,extrovert, or etc.I promised myself that I would never judge a person without knowing them.As time passes by, I didn't notice that I was judging other people already. I really don't want to judge other people but the person itself wants to be judge but sometimes I think that maybe I didnt try hard enough to get to know them well.