Even low-calorie diets and vigorous exercise fail to work in the long term for at least some people.

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

I believe that it may be normal, healthy, and even productive to experience mild to moderate depression from time to time as part of the variable emotional spectrum, either as an appropriate response to situations or as a way of turning inward and mentally chewing over problems to find solutions.

Everyone prefers some foods over others, but some adults take this tendency to an extreme. These people tend to prefer the kinds of bland food they may have enjoyed as children - such as plain or buttered pasta, macaroni and cheese, cheese pizza, French fries and grilled cheese sandwiches - and to restrict their eating to just a few dishes.

I tried to change the conventional paradigm, for example, by insisting on the reality of mind-body interaction, by stressing the importance of natural therapies, by focusing attention on lifestyle issues, by looking at worthwhile aspects of alternative medicine. Many people have been threatened by that. Doctors especially tend to think that they know everything about the human body, and don't realize that medical education has really omitted many very important subjects.

The notion that a human being should be constantly happy is a uniquely modern, uniquely American, uniquely destructive idea.

As an American, you have a right to good health care that is effective, accessible, and affordable, that serves you from infancy through old age, that allows you to go to practitioners and facilities of your choosing, and that offers a broad range of therapeutic options.