"Flow" has been called an "optimal experience." It's a state of "effortless concentration so deep that [the persons in the flow] lose their sense of time, of themselves, of their problems."
There are two forms of mental effort: "concentration on the task and the deliberate control of attention." When you're in the flow, the deliberate control of attention comes naturally: it just occurs without trying. The "resources" that would be spent on trying to control your attention can, instead, be spent on the task at hand, thereby making you more effective when dealing with the task at hand.
Adapted from Daniel Kahneman, Thinking, Fast and Slow.
The only problem is, now that I realize what is occurring when I get immersed in a project, my resentment at interruptions has increased (and it has always been at a fairly high level; I think I was happiest at the Notre Dame Law School library, where utter silence was expected at all times). It has made me a bit more prickly at the office. My job affords a lot of opportunities every day to get into the flow, which is great and is probably why I enjoy my job. But the office environment affords even more opportunities for disruptions, and that tension--flow v. interruptions; flow broken by interruptions--is mentally brutal.
(For whatever reason, the 512-page Kindle edition of Kahneman's fascinating book is only $2.99.)
