Killingsworth, M. A., and D. T. Gilbert. 2010. “A Wandering Mind Is an Unhappy Mind.” Science 330 (6006) (November 11): 932–932. doi:10.1126/science.1192439.
We developed a smartphone technology to sample people’s ongoing thoughts, feelings, and actions and found (i) that people are thinking about what is not happening almost as often as they are thinking about what is and (ii) found that doing so typically makes them unhappy.