Book excerpt: Stress is not in your head, it’s in your body—this is the key to peak performance that Leah Lagos, PsyD, BCB, an internationally known expert in biofeedback and sport and performance psychology, wants us to know. In this book, she shares with readers for the first time the same program that she uses with top athletes, CEOs, business leaders—anyone who wants and needs to perform at their best. What makes her scientifically proven 10-week program unlike any other is that she recognizes the link between heart rhythms and stress to create specific, clinically tested exercises and breathing techniques that allow you to control your body’s physical response to stress. She pairs this training with cognitive-behavioral exercises to offer a two-tiered process for strengthening health and performance, enabling readers to respond more flexibly to stressful situations, let go of negative thoughts and emotions, and ultimately be more focused and confident under pressure.