The mindless following of routine and other automatic behaviors lead to much error, pain and a predetermined course of life, contends Langer, Harvard professor of psychology, in this thought-provoking study in which she "translates" for lay readers the findings of her research, much of it among the elderly. With anecdotes and metaphors, she explains how the mindless--as opposed to the mindful--develop mindsets of categories, associations, habits of thought born of repetition in childhood and throughout schooling. To be mindful, she notes, stressing process over outcome, allows free rein to intuition and creativity, and opens us to new information and perspectives. Langer discusses the negative impact of mindsets on business and social relations, showing special concern for the elderly, who often suffer from learned helplessness and lack of options. Encouraging the application of mindfulness to health, the author affirms that placebos and alternative, mind-based therapies can help patients and addicts move from unhealthy to healthy contexts. First serial to Health magazine; QPBC, Library of Science, Behavioral Science, Natural Science and Psychotherapy and Social Science Book Clubs selections. Publishers Weekly ( )