Mind your coffee cup
We have to make the effort to bring it to the sink for a thorough washing - to get rid of these brown marks of abuse, the residue of neglect. I flush it with hot boiling water, to kill the germs and cleanse the inner surface. Neglect - can become a habit. Piled up layers of neglect would result in cup so dirty that one would think it was brown. Consistency breaks the chain.
Your mind is like a coffee cup - be proud of it and clean it regularly.