Wikipedia: “In his seminal work, Flow: The Psychology of Optimal Experience, Csíkszentmihályi outlines his theory that people are happiest when they are in a state of flow—a state of concentration or complete absorption with the activity at hand and the situation. It is a state in which people are so involved in an activity that nothing else seems to matter. The idea of flow is identical to the feeling of being in the zone or in the groove. The flow state is an optimal state of intrinsic motivation, where the person is fully immersed in what he is doing. This is a feeling everyone has at times, characterized by a feeling of great absorption, engagement, fulfillment, and skill—and during which temporal concerns (time, food, ego-self, etc.) are typically ignored.”

My buddy Henry has been praising this book for years and I finally got around to reading it.