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?

The retail industry has its own headache: it loses $16 billion a year to customers who buy clothes, wear them with the tags tucked in, and return these secondhand clothes for a full refund.

People are willing to work free, and they are willing to work for a reasonable wage; but offer them just a small payment and they will walk away.

If you ever go bar hopping, who do you want to take with you? You want a slightly uglier version of yourself. Similar ... but slightly uglier.

People are irrational - and predictably so.

Imagine you owe on five credit cards, you owe five debts. So which debt should you pay first? And the answer is very simple: You should pay the one with the highest interest rate first. But that's not what people do.

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.