Proposed by Mihály Csíkszentmihályi, this positive psychology concept is referenced in many fields. Flow is the mental operation which one performs an activity and is immersed in a feeling of energized focus, full involvement, and enjoyment of an activity. In essence, it's characterized by complete absorption in what one does.
According to Csikszentmihalyi, flow is focused motivation. A single-minded immersion, and represents the maximum experience in harnessing emotions in the service of performing and learning. In flow, emotions are not contained and channeled. They are positive, energized, and aligned releases of the task at hand. To be caught in a the lull of depression, or agitation of anxiety is to bar flow. The hallmark of flow is a feeling of spontaneous joy, and rapture, while performing a task. Flow is also described as a deep focus on the activity – not one's self or emotions. Buzz terms, or similar mental states, include: being in the moment, present, in the zone, on a roll, wired in, in the groove, on fire, in tune, centered, or focused.