One of the things psychologists used to say was that if you are depressed, anxious or angry, you couldn't be happy. Those were at opposite ends of a continuum. I believe that you can be suffering or have a mental illness and be happy - just not in the same moment that you're sad.

Some find that very optimistic people have benign illusions about themselves. These people may think they have more control, or more skill, than they actually do. Others have found that optimistic people have a good handle on reality. The jury is still out.

Positive emotion can be about the past, the present, or the future. The positive emotions about the future include optimism, hope, faith, and trust. Those about the present include joy, ecstasy, calm, zest, ebullience, pleasure, and (most importantly) flow; these emotions are what most people usually mean when they casually-but much too narrowly-talk about "happiness." The positive emotions about the past include satisfaction, contentment, fulfillment, pride, and serenity.

The pursuit of happiness is enshrined in the Declaration of Independence as a right of all Americans, as well as on the self-improvement shelves of every American bookstore. Yet the scientific evidence makes it seem unlikely that you can change your level of happiness in any sustainable way. It suggests that we each have a fixed range for happiness just as we do for weight. And just as dieters almost always regain the weight they lose, sad people don't become lastingly happy, and happy people don't become lastingly sad.

Changing the destructive things you say to yourself when you experience the setbacks that life deals all of us is the central skill of optimism.

The belief that we can rely on shortcuts to happiness, joy, rapture, comfort, and ecstasy, rather than be entitled to these feelings by the exercise of personal strengths and virtues, leads to legions of people who, in the middle of great wealth, are starving spiritually.

There are physical characteristics which are inherited. These include things like good looks, high intelligence, physical coordination. These attributes contribute to success in life, and success in life is a determinant of optimism.