How would you like to spend a month without buying any new stuff? Elizabeth Kwak-Heffernan is giving it a try, exempting "food and certain toiletries" but allowing herself "buying used stuff from resale shops or Craigslist."
For the purposes of the exercise, obviously there's a difference between buying new and buying used. But the magic of economic equilibrium is such that if you're trying to influence the way the world "gobbles up new resources to build still more stuff — much of which we don’t even need" this probably won't work. If enough people shift out of buying new cars and into buying used cars to make an impact on anything, for example, that will push up the resale value of cars. And since non-shifters' ability to trade in their old cars for new ones is in part a function of the resale value of their old cars, the shifters are making it more likely that the non-shifters will buy new cars.