Growing up in Dublin, John Kavanagh was bullied. After suffering a bad beating when he intervened to help a woman being attacked, he decided to learn to defend himself. Before long, he was training fighters in a tiny shed, and promoting the earliest mixed-martial arts events in Ireland. And then, a cocky kid called Conor McGregor walked into his gym. Here, Kavanagh tells his own remarkable life story—which is at the heart of the story of the explosion of MMA in Ireland and globally. Kavanagh has become a guru to young men and women seeking to master the arts of combat, and as McGregor's trainer, his gym has become a magnet for fighters from all over the world. Kavanagh's portrait of McGregor is a revelation. What emerges is a remarkable portrait of ambition, discipline, and persistence in the face of years and years of disappointment. It is a must read for every MMA fan—and anyone who wants to understand how to follow a dream and realize a vision.