In the 1970s, University of Chicago psychologist and department chairman Mihaly Csikszentmihalyi (mee-hi chick-sent-mee-hi) began using the term “flow states” ” (for the ease at which water flows around stone) to describe Maslow’s “peak experiences.” Csikszentmihalyi defined flow as "being so involved in an activity that nothing else seems to matter; The ego falls away. Time flies. Every action, movement and thought follows inevitably from the previous one, like playing jazz. Your whole being is involved, and you're using you skills to the utmost."
He also found that the experience itself is so enjoyable that people will do it even at great cost, for the sheer sake of doing it. When a person is entrenched in a such a state, as Csikszentmihalyi points out in his book Flow, "they stop being aware of themselves as separate from the actions they are performing." In other words, time and space vanish, self vanishes, and the now swallows us whole.
The range and depth of the flow experience varies considerably, but exceptionally heightened performance accompanied by exceptionally heightened pleasure are the most consistent markers (Jackson 1996). Temple University Sport Psychologist Michael Sachs, who has also made an extensive study of flows states—defined for his purposes as “increased sense of well being, an enhanced appreciation of nature, and a transcendence of time and space”—found they vary from pleasant highs to nearly unbearable bliss (Kotler, 2006). At the far end of the spectrum sits a new species of juju: a godlike-like sense of power and invincibility, out-of-body experiences, the occasional orgasm (Battista 2004; Cooper, 1998; Csikszentmihalyi and Jackson, 1963; Hoffman and Novak 1996).