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

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.

Money is a great way to get happiness. Right? Lots of wonderful things you can do with money. The question is, are we really optimizing on that? So, if you think about getting lattes and getting cable. Which one of those is actually giving you a greater happiness, and if you have to cut on one of those, which one would you cut? So, I think thinking in terms of concrete terms would help us a great deal.

People are irrational - and predictably so.

In life we encounter many people who, in some way or another, try to tattoo our faces.

Money is all about opportunity cost. Every time you spend on something, that's something you can't spend on something else.

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.