Not all debt is bad. From time to time we should get into debt when there's a good reason for that.

In total, by giving people $30 bonus, Intel lost almost 5 percent of productivity. That's a lot. Now, think about it. You give money because you think this would increase motivation. It actually decreases motivation.

But suppose we are nothing more than the sum of our first, naive, random behaviors. What then?

Kids don't care what party they have, right? They want cake and they want to run around. Nothing else matters. But in this escalation, all the kids want parties like their friends. So, if all the friends have an amazing, expensive party, they all want the same thing. If we all got to scale down as a coordinated effort, all the kids would have been just as happy.

What you should do is wait until the end of each month, and then say, "OK, how much money do I have? How much do I need? Let me send the rest to retirement."

There's something about [cyclically] doing something over and over and over that seems to be particularly demotivating.

I don't want to say that the poor are inherently cognitively diminished, but at the end of the day of making difficult, tough decisions, it's very hard to have the energy to think about things with the right mindset.