Happiness is determined by factors like your health, your family relationships and friendships, and above all by feeling that you are in control of how you spend your time.

Friends are sometimes a big help when they share your feelings. In the context of decisions, the friends who will serve you best are those who understand your feelings but are not overly impressed by them.

It's a wonderful thing to be optimistic. It keeps you healthy and it keeps you resilient.

People should be conscious of the large contribution made by anything that gets people together easily in the reduction of loneliness and emotional well-being.

Question: So investors shouldn't delude themselves about beating the market? Answer: "They're just not going to do it. It's just not going to happen."

I have always believed that scientific research is another domain where a form of optimism is essential to success: I have yet to meet a successful scientist who lacks the ability to exaggerate the importance of what he or she is doing, and I believe that someone who lacks a delusional sense of significance will wilt in the face of repeated experiences of multiple small failures and rare successes, the fate of most researchers.

To know whether you can trust a particular intuitive judgment, there are two questions you should ask: Is the environment in which the judgment is made sufficiently regular to enable predictions from the available evidence? The answer is yes for diagnosticians, no for stock pickers. Do the professionals have an adequate opportunity to learn the cues and the regularities? The answer here depends on the professionals' experience and on the quality and speed with which they discover their mistakes.