It’s time to begin trading gains in productivity for time instead of for stuff. A study by the Center for Economic and Policy Research found that simply by cutting our work time to European levels, we could reduce our energy use and carbon footprint by 25-30 percent. It would also make us happier—Forbes magazine reported that the four happiest nations on earth—Denmark, Finland, the Netherlands, and Sweden—are all characterized by the comparatively short working hours and attentiveness to work-life balance.