Optimistic people play a disproportionate role in shaping our lives. Their decisions make a difference; they are inventors, entrepreneurs, political and military leaders - not average people. They got to where they are by seeking challenges and taking risks.

Groups tend to be more extreme than individuals.

Survival prospects are poor for an animal that is not suspicious of novelty.

Ten minutes of a smartphone in front of your nose is about the equivalent of an hour long walk in bright daylight. Imagine going for an hour long walk in bright daylight and then thinking, "Now I'll get some sleep." It ain't going to happen.

We are often confident even when we are wrong, and an objective observer is more likely to detect our errors than we are.

So your emotional state really has a lot to do with what you're thinking about and what you're paying attention to.

An investment said to have an 80% chance of success sounds far more attractive than one with a 20% chance of failure. The mind can't easily recognize that they are the same.