Author argues one of the critical components of flow is a complex self: a self that can weather change & maintain serenity. flow- experience is to concentrate attention on present moment instead of continually struggle with the past or worry about tomorrow. Ofcourse with potentially stress of daily life , book discusses how flow experiences can reduce stress. Author argues that flow will produce happiness, creates an opportunity for cultures to evolve.
“We have all experienced times when, instead of being buffeted by anonymous forces, we do feel in control of our actions, masters of our own fate. On the rare occasions that it happens, we feel a sense of exhilaration, a deep sense of enjoyment that is long cherished and that becomes a landmark in memory for what life should be like….. moments like these are not the passive, receptive, relaxing times…the best moments usually occur when a person’s body or mind is stretched to its limits in a voluntary effort to accomplish something difficult and worthwhile.”
But I should say, distinguish between simple pleasure and enjoyable flow is largely semantic & very unconvincing. And It was very interesting to find out that, this whole theory was applied while designing video games(which infact is addictive faux flow experience). flow is simply feeling of pleasure and like others this too can be addictive and its not an good.
Book is good(heavy) read if you are interested in Psychology.
You can also watch Mihaly Csikszentmihalyi discussing at TEDtalk