Stefan G. Hofmann, PhD, is professor of psychology in the department of psychological and brain sciences at Boston University. He has been president of numerous professional organizations, and is currently editor in chief of Cognitive Therapy and Research. He has published more than 400 peer-reviewed journal articles and twenty books. He is a highly cited researcher, and has received many awards, including the Humboldt Research Award. His research focuses on the mechanism of treatment change, translating discoveries from neuroscience into clinical applications, emotion regulation, and cultural expressions of psychopathology. He is codeveloper (with Steven C. Hayes) of process-based therapy. Steven C. Hayes, PhD, is Nevada Foundation Professor in the department of psychology at the University of Nevada, Reno. He has been president of numerous professional organizations, is author of forty-five books and nearly 650 scientific articles, and is among the most cited living psychologists. He has shown in his research how language and thought leads to human suffering, and is originator and codeveloper of acceptance and commitment therapy (ACT): a powerful therapy method that is useful in a wide variety of areas; relational frame theory (RFT): an empirical program in language and cognition; and process-based therapy (with Stefan G. Hofmann). David N. Lorscheid is a psychological coach and science writer. After completing his BSc in psychology at the Radboud University in Nijmegen, Netherlands, he moved to Vienna, Austria to coach people with low self-esteem and social anxiety. He started giving in-person seminars and online workshops, working with thousands of people from more than thirty different countries. He became a public speaker and advocate for mental health, giving talks in three different languages in six different countries. He also became a science writer, translating evidence-based principles from psychotherapy into practical advice for everyday life. His texts have been read by over a million people in more than forty different countries.