Ethan Kross, professor of psychology at the University of Michigan, has spent years studying how people talk to themselves and the effect that this "chatter" has on our performance. From professional athletes to top students and senior executives, even the most talented among us sometimes struggle to quiet the voices in our heads. And Kross says that, while some self-talk can help us, it's often unproductive. He offers tips and tricks to break out of negative thinking and get back on track, especially at work. He's the author of the book “Chatter: The Voice in Our Head, Why it Matters, and How to Harness It.”