Most people start claiming benefits within a year of when they become eligible, although benefits increase substantially if they wait.

Maybe you'll take the cash out. So a credit card company or a bank that goes into the business of saying we're going to be the broker, we're going to sell you a mortgage that you're going to be able to pay off, we're going to help you reduce your credit card debt, we're going to help you save for retirement, we're going to put you into mutual funds that have low fees rather than high fees.

There's a second component of a good savings plan, which is something that a colleague of mine called Schlomo Benartzi and I developed many years ago, that we call "save more tomorrow."

When should we nudge and when should we shove, I think, it's a political judgment. Obviously in some situations we need shoves, we need laws. Fraud is against the law, murder is against the law, drunk-driving is against the law. We don't need just nudges.

Most economists, including me, agree that longevity insurance would make sense for a lot of people.

So the world is much more correlated than we give credit to. And so we see more of what Nassim Taleb calls "black swan events" - rare events happen more often than they should because the world is more correlated.

Recall that people like to do what most people think it is right to do; recall too that people like to do what most people actually do.