Mihaly Csikszentmihalyi is professor psychology at the University of Chicago. He is the father of the notion of Flow. Csíkszentmihályi outlines his theory that people are most happy when they are in a state of flow— a state of concentration or complete absorption with the activity at hand and the situation. 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 or she 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. He is the author of many books among which I have read two of them:
It has been a few years since I read them , but now I came across very good interviews where he is explaining himself the concept of flow and gives examples with painters and artists. There is even a TED talk from 2004 published in 2008.
Mihaly Csikszentmihalyi: Creativity, fulfillment and flow
Interview with Mihaly Csikszentmihalyi on Flow & Performing Art
The last 2 videos are interview with him in Dutch, but still it is translated with subtitles:
FLOW – Mihaly Csikszentmihalyi (part 1/2)
FLOW – Mihaly Csikszentmihalyi (part 2/2)