In a deal with my covenant partner, I have been persuaded to guard my mouth a little closer than normal :)
Negativity in how we speak is equally as evil as profanity.
I think some Christians think bible verses about guarding our lips is merely about profanity, or socially offensive language. It is actually so much more.
Saying you CAN’T do something, or “I’m stupid” are equally as offensive to the Lord as profanity and detrimental to our walk with the King. We are righteous through Christ. We can do ALL things through Him! I am NOT stupid. I am NOT fat. I am NOT giving up!

Psalm 141:3 Set a guard, O Lord, over my mouth;
Keep watch over the door of my lips.

Proverbs 21:23 Whoever guards his mouth and tongue
Keeps his soul from troubles.

So I WILL watch my mouth. I will be victorious over it.  James 3 says a lot of our tongue. 6 And the tongue is a fire, a world of iniquity. The tongue is so set among our members that it defiles the whole body, and sets on fire the course of nature; and it is set on fire by hell.

We must tame our tongue. We must watch what we say so we do not hinder our victories!