We deeply want to be led by people who know what they're doing and who don't have to think about it too much.

Individual investors predictably flock to stocks in companies that are in the news.

The brains of humans contain a mechanism that is designed to give priority to bad news.

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.

We were required to predict a soldier's performance in officer training and in combat, but we did so by evaluating his behavior over one hour in an artificial situation. This was a perfect instance of a general rule that I call WYSIATI, "What you see is all there is." We had made up a story from the little we knew but had no way to allow for what we did not know about the individual's future, which was almost everything that would actually matter. When you know as little as we did, you should not make extreme predictions like "He will be a star."

If you can't take the time for a vacation right now, or even a night out with friends, put something on the calendar - even if it's a month or a year down the road. Then whenever you need a boost of happiness, remind yourself about it.

Organizations may be better able to tame optimism than individuals are.