Once you break the social norm and create a new social norm, all of a sudden it can stay with us for a long time.

In the U.S., I think there is an ideology of not telling kids what to do. Nobody to tell you who to marry, not tell you what job to pick. You're your own person. You have the freedom to choose, including the freedom to fail in magnificent ways. And I think that's the big difference. In other countries there is basically a social norm about saving that is passed from generation to generation. In the U.S. there isn't.

You can think about life as a battle between you and a doughnut shop. The doughnut shop wants you to eat another doughnut and pay the money, and you want to do it in the short term, but in the long term it's not good for you either financially or from a health perspective.

The problem with opportunity cost is that opportunity cost is divided among many, many things.

Your immediate environment is comprised of coffee shops, supermarkets, websites, apps and all kinds of things - none of which have an interest in your long-term or short-term financial well-being.

The people who need to overcome temptation to the highest degree have the hardest time doing it.

Money is a wonderful invention. It lets us save, it lets us specialize, right? I couldn't be a professor if there wasn't any money. Every day I would have to raise chicken and bread and broccoli and go ahead and spend all my time trading. So, money is a wonderful mechanism.