Until the early 1970s, credit was available to most people only for significant purchases—a home, car, or big piece of furniture—where the lender had something valuable to recover if the borrower fell behind in the payments. Lenders were cautious about loans and made sure they had an easy way to recover the money if anything went wrong. For most purchases, people saved until they had enough to pay cash.

That changed with the introduction of credit cards in the 1970s. Lenders discovered a huge and profitable new market of borrowers. And we, the credit card spenders and borrowers, discovered the convenience of cash-free spending and the pleasure of getting what we wanted without waiting until we had the cash to pay for it. Sure, some people got into debt trouble and ended up unable to pay their credit card bills. But the money the credit card companies made on the majority of customers who kept up with their payments more than balanced out those losses.

Which leads us to where we are today. We live in an age of easy credit. And that requires a new kind of financial discipline and self-control. Credit makes it easy for us to get what we want. But it also makes it easy to get into serious financial trouble.