Many exercise forms - aerobic, yoga, weights, walking and more - have been shown to benefit mood.

Short naps are good. Given modern workplace demands, this is not possible for many people - but if you have the option, try napping for ten to twenty minutes in the afternoon, preferably lying down in a darkened room.

As an undergraduate at Harvard in the 1960s, I was fascinated by my visits to psychologist B.F. Skinner's laboratory.

Fear and greed are potent motivators. When both of these forces push in the same direction, virtually no human being can resist.

Another very common use, in all cultures, of psychoactive substances is to give people transcendent experiences. To allow them to transcend their human and ego boundaries to feel greater contact with the supernatural, or with the spiritual, or with the divine, however they phrase it in their terms.

I think it's worth trying to do something about obvious sources of stress in your life. But even more important is learning and practicing methods to neutralize the harmful effects of stress on the body and mind. There are many possibilities, anything from meditation and yoga to listening to relaxing music. My personal favorite is simple breathing techniques - they're very effective, take very little time, and they're free.

More than one skillful physician has said that if one asks the right questions, the patient will make the diagnosis for you in his or her own words.