Duhigg explores the scientific mechanisms behind habits—how they form, how they work in our brains, and how we can change them. He visits neuroscience labs, examines corporate transformation, and delves into real‑life examples (e.g., Olympic athletes, major companies, social movements) to argue that by understanding the “habit loop” (cue → routine → reward) and focusing on “keystone habits,” individuals and organisations can achieve lasting change.