"We are what we repeatedly do," said Aristotle. "Excellence, then, is not an act, but a habit." On the most basic level, a habit is a simple neurological loop: there is a cue (my mouth feels gross), a routine (hello, Crest), and a reward (ahhh, minty fresh). Understanding this loop is the key to exercising regularly or becoming more productive at work or tapping into reserves of creativity. Marketers, too, are learning how to exploit these loops to boost sales; CEOs and coaches are using them to change how employees work and athletes compete. As this book shows, tweaking even one habit, as long as it's the right one, can have staggering effects.