Ross Edgley is the first man to swim around Great Britain and Iceland. He is also the only person I’m aware of to finish a marathon while pulling a Mini Cooper and complete a triathlon with a 45kg tree attached to him, among other impressive feats. His book, The World's Fittest Book, which details his key training philosophies, opens with one of my favourite quotes: “As to methods, there may be a million and then some, but principles are few. The man who grasps principles can successfully select his own methods.”
This quote, widely attributed to American engineer Harrington Emerson, is pertinent to anyone wanting to get in shape – not just world record-breaking adventurers.