I was in a class back several years ago where the instructor gave a memorable less about inner monologues. He pulled up two volunteers and asked one to explain a new concept to the other. Good, fine, everything went well. The second person repeated the concept back clearly and in their own words.

Then the instructor asked them to explain a different concept. This time the instructor whispered in the second person's ear (loud enough for the class to listen), "you're stupid, you're never going to understand this, everyone thinks you're an idiot, you should just quit," and on and on. And of course the person hadn't retained anything. The point being just how much negative self-talk interferes with learning and communication.