The feature would allow the user to type some text conveying some idea to themselves that they want to keep top-of-mind. This could be a new belief about themselves/the world that they are coaching themselves to believe OR it could be a description of a goal they want to attain.
It could be styled similar to the daily quote / affirmation, but it would remain the same every day until the user went in to change it. It could have a character limit to keep it minimal and not too distracting, yet still effective.