Mihaly started to study adults who engaged in other activities -people who were long-distance swimmers, or rock climbers, or chess players. He only looked at first at nonprofessionals. Often they were doing things that were physically uncomfortable, exhausting, and even dangerous, for no obvious reward- -yet they loved it. He talked to them about how they felt when they were doing the thing that drew this extraordinary focus out of them. He noticed that although these activities were very different, the way the people described how they felt had striking similarities. One word kept cropping up again and again. They kept saying things like: "I was carried on by the flow."

— Stolen Focus by Johann Hari (Page 54)