We must take responsibility of what we speak because we will act them. You have to pay attention to the word that will come out in your mouth. You have to get comfortable inside your head because you will be expressing them in words.
Every day, we watch our speech when we talk to people. As I said, we pick most of our words base on the experience and information we gathered and stored in our minds. The brain will filter all those things and as a result it creates beliefs.