Experts say entrepreneurs, athletes, and writers all enter 'flow state' when they really concentrate on the task at hand — it's a reward in itself but also can increase productivity 

IT DOESN’T happen to me very often — ‘flow’. Flow, in positive psychology, means being so completely immersed in your task, having such a full focus that even though the task might be complex, it’s enjoyable and you’re getting it done, writes Colm O’Regan