The Mastery of Destiny is a self-help book by James Allen that explores the concept of personal empowerment and the ability to shape one's own life. Published in 1909, the book emphasises that individuals have the power to create their own destiny through thoughts, attitudes, and actions. Allen argues that by mastering one's thoughts and emotions, one can achieve success and fulfilment. The book encourages readers to take responsibility for their lives and cultivate positive habits to attain their desired outcomes.