" Cravings are what drive habits. And figuring out how to spark a craving makes creating a new habit easier. It’s as true now as it was almost a century ago. Every night, millions of people scrub their teeth in order to get a tingling feeling; every morning, millions put on their jogging shoes to capture an endorphin rush they’ve learned to crave. "

― Charles Duhigg , The Power of Habit: Why We Do What We Do in Life and Business