Why was Edison able to invent the light bulb, or why was Reinhold Messner the first person to summit all eight-thousanders? The belief in one's own abilities plays a crucial role in answering this question. People who face a series of challenges on their way to their goals and do not give up even when others have long retreated are convinced of themselves, their strength, and their capabilities. They trust that there is a solution and are not easily discouraged by failures. Such a strong belief in one's own abilities and the success of an action is referred to in the academic world as high self-efficacy. This book explores the background of high self-efficacy, which serves as a driving force for success and life satisfaction, and explains how it works.