The Marginal Principle

The marginal principle is a simple rule of thumb to help you think through getting the most out of life. It really comes down to the idea that if something's worth doing, you should keep doing it until your marginal benefits from doing more of it are just equal your marginal costs. We're going to put all our concepts opportunity, cost, thinking at the margins to work by taking a very very expensive car ride across manhattan. Do you want one more chunk of planet money? We'll be waiting for you.