Establish a closing ritual. Know when to stop working. Try to end each work day the same way, too. Straighten up your desk. Back up your computer. Make a list of what you need to do tomorrow.

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."

We have associations to things. We have, you know, we have associations to tables and to - and to dogs and to cats and to Harvard professors, and that's the way the mind works. It's an association machine.

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.

Most people are highly optimistic most of the time.

Every night for the next week, set aside ten minutes before you go to sleep. Write down three things that went well today and why they went well...Writing about why the positive events in your life happened may seem awkward at first, but please stick with it for one week. It will get easier. The odds are that you will be less depressed, happier, and addicted to this exercise six months from now.

In strategic decisions, I'd be really concerned about overconfidence.