Flow

Pronunciation:  \‘flō\     v. 4 a: to proceed smoothly and readily

--Merriam-Webster, Online

Flow

        Flow is the mental state of operation in which the person is fully immersed in what he or she is doing by a feeling of energized focus, full involvement, and success in the process of the activity (proposed by positive psychologist Mihály Csíkszentmihályi.)

        Colloquial terms for this or similar mental states include: to be on the ball, in the zone, or in the groove.

--Wikipedia