This question is a condensed way of considering all of the questions I would ask of any spontaneous opportunity that intercepts me during the day.  ”Is the time commitment worth the value of the experience?” ”Do I miss this person’s influence in my life?” ”Will this inhibit my accomplishment of a time-sensitive goal?”  ”Is the emotional gratification enough to out-weigh the productivity loss?” 

That little question/habit helps me make better decision, feel better about my decisions, and I believe, feel happier over time.