When we save, everybody in the household is just suffering. By having the coin in a visible way, when you scratch, you can say the person that is in charge of the making money for the family is doing the right thing.

A very simple bad decision is to get into debt. And that is very expensive.

When it comes to the mental world, when we design things like health care and retirement and stock markets, we somehow forget the idea that we are limited. I think that if we understood our cognitive limitations in the same way that we understand our physical limitations … we could design a better world.

If you want to spend more money in restaurants, use credit cards more than cash. If you want to spend less, use cash more than credit cards. But in general, we can think about how to use the pain of paying and how much of it do we want. And I think we have like a range. Credit cards have very little pain of paying, debit cards have a little bit more because you feel like today, at least it is coming out of your checking account, and cash has much more.

Why would you take money out of your paycheck at the beginning of the month when you don't know how much money you'll need?

Rainy day savings are incredibly important, because from time to time, bad things happen. And if you're not prepared for that, it's going to be really terrible.

None of us always make the best financial decisions.