This slim volume, skinnier than a size-zero model, belongs to the increasingly tiresome genre of clever-dick lit. If you have heard of Blink, Nudge, Snark or Freakonomics, you’ll know the form; indeed you could probably write one yourself. Choose a proverb, any old proverb: ‘more haste, less speed’, say. Reformulate it as a cute title – Trudge: What the Tortoise Can Teach Us About Wealth, Health and Happiness – and the book more or less writes itself. Sit back and wait for Barack Obama or David Cameron to be seen reading it. You are now officially a guru.