We have exactly five senses, and two of those senses are crucial to telling us what is going on around us. One of those senses is generally used to communicate with.
Language is crucial to our experience as human beings. Thoughts we think are often turned into words, we do not typically turn our thoughts into visuals or into feeling sensations or tastes or smells, even though we often can.
Because sound has direct access to the meaning-making parts of our brain, we can short-circuit our normal mental lives with a carefully-tailored statement.
Saying something over and over again is like picking up heavy weights over and over again, it strengthens those parts of being by forcing it to accommodate the repetition.