You can live to be a hundred and enjoy each of those years as a fully functioning person--or so says Chopra (Unconditional Life, 1991, etc.) in this challenging work. An intriguing set of Census Bureau statistics cited here notes that the number of centenarians is twice what it was ten years ago- -and is expected to double again by the millennium. Prolonging fruitful lives is not a question of mind over matter, Chopra contends, but, rather, of mind and matter--mind and body--together at one with the universe. It's often hard for pragmatic Westerners to deal with this kind of mind/spirit/body talk, but Chopra has a talent for anchoring the ephemeral in what's generally considered reality, and for leading spiritual novices through the swamps of such concepts as awareness, detachment, and self without resorting overly to New Age slang. In discussing how awareness--or lack of it--affects the physical symptoms of aging, for instance, Chopra builds an authoritative base using research from Harvard, Duke, and Stanford that shows that mental, social, and intellectual activity can keep people vital and alert as they age. But because many of us have poor models for aging, we accept the idea that getting old means pain, intellectual decay, and inactivity. Bringing attention or awareness to areas of discomfort is the first step to changing problems, Chopra argues, offering a step-by-step routine to make one or more of those changes. Along with reflections on such provocative concepts as cellular memory and ``metabolizing time,'' the author also tackles the positive aspects of aging--creativity and wisdom--and the value of those old standbys, diet and exercise. A separate chapter examines, not altogether satisfactorily, India's traditional medical system of Ayurveda. A guide to longevity that's also a thoughtful and sometimes inspiring reflection on our remarkable place in the cosmic scheme of things.