"My book THE FOUR TENDENCIES is about a personality framework that I’ve identified called the Four Tendencies that divides all of humanity into four types: Upholder, Questioner, Obliger, and Rebel. I got my first insight into this framework when I had lunch with a friend and she said something that got me obsessed with this question of personality types. She said, 'I know I would be happier if I would go running, and when I was in high school I was on the track team and I never missed track practice, so why can’t I go running now?' And I thought, 'Well, why? It’s the same person, the same behavior, at that time it was effortless but now she can’t do it. What’s going on?' My determination to figure out the answer to that question, in the end, led me to write a whole book, called THE FOUR TENDENCIES."