Performance coach Adrian Kelly's new book, The Success Complex, explores what success means. He challenges misconceptions about the core skills vital to overcome challenges, mixing stories of historical figures with those of modern sports stars.
At 28, Natalie Crawford was diagnosed with cystic fibrosis. She wasn't supposed to run at all, let alone complete four marathons. But Natalie didn't let medical orthodoxy set her boundaries - and in dong so has changed how the world looks at CF and exercise.
Molly Butterworth nearly didn't become a runner at all. Her first passion was swimming and she took some persuading to run a cross-country event. Now she runs for England, has one eye on the Olympics and is a successful coach.
Addison Hendricks was running 130 miles on a track to break American distance records when he was just 16. These days, the 26-year-old races - and wins - events that stretch to 400 miles and are put on by the legendary Lazarus Lake.