Smokers paid more for their cigarettes by purchasing them one pack at a time instead of by the carton. Dieters did not stock any ice cream in the freezer. Academics (including me) would commit themselves to present a paper that was still a work in progress at a conference several months off, to give themselves an incentive to finish it. People who had trouble getting up in the morning put their alarm clocks on the other side of the room so they could not just reach over and switch off the alarm without getting out of bed.
