Most people are living longer lives, but not necessarily in good health. It is therefore timely that the new book Am I My Body’s Keeper? Torah, Diet, Science, and Fitness – for Life focuses on how to achieve both.The author, Michael Kaufman, writes from the perspective of a religiously observant Jew. Accordingly, the book includes quotations from Jewish sages on the subject of healthful practices – most prominently those of Maimonides (Rambam), the medieval rabbi-philosopher-physician whose guidelines on proper diet, exercise, sleep and attitude are incorporated in many modern Jewish works for their timeless wisdom.Kaufman admits up front that he has no academic certification in medicine, health, diet, fitness or exercise. Rather, he has read “the extensive publications and reports of governmental health organizations and scientific research studies on the subject.”The book’s 798 footnotes cite sources ranging from the Shulhan Aruch (Code of Jewish Law) to articles in The New York Times and academic journals to Harvard Medical School reports.Impressive as that number of citations may be, it’s only a drop in the vast ocean of health-related information available today. Anyone writing a book of this nature must choose which data to trust – a difficult task, given that much information is contradictory, inconclusive, outdated or flawed.No single volume, including this one, can encompass every study, opinion and discovery, nor can it resolve every contradiction.The author can only strive to present information that seems as well-corroborated and commonsensical as possible, yet informed readers can find legitimate space for questioning certain statements. Passages that raised flags for me included a dismissive remark about olive oil (for a fuller treatment, I recommend the “Olives” chapter in Chana Bracha Siegelbaum’s The Seven Fruits of the Land of Israel with Their Mystical and Medicinal Properties); contradictory statements on haredi health habits and longevity; no mention of safe and unsafe sources of fish in his list of the top 10 healthiest foods; and advice to “leave a little on the plate” rather than taking less food on the plate to begin with.However, Kaufman’s overall approach is solid beyond a doubt. He wrote this book in his 86th year of what he describes as exceptionally good health, and actively practices what he preaches.The crux of what he exhorts is the essential value of adequate exercise in maintaining a fit body and mind. Following Maimonides (“Anyone who does not exercise will end his days in pain”), he puts a value on exercise even higher than on diet and subscribes to the latest research suggesting that sitting is the new smoking.He advises readers to “stand, move and walk as often as you can during the day,” sharpening the point by stating that “being sedentary for eight hours a day either at the office or in a yeshiva or kollel is bad for your health.” His exhortations tend to be repetitive, perhaps meant to hammer home the point.Kaufman, a Jerusalem resident, brings examples from his own life, such as describing how he fashioned a low-cost standing desk from a shtender. His five key lifestyle behaviors “known to reduce the risk of chronic diseases” and even heal such diseases are well known but nevertheless worth repeating: not smoking; exercising regularly; avoiding or drinking alcohol only in moderation; maintaining a healthy body weight; and getting sufficient sleep.Jewish scholars throughout the ages had unequivocal views on this issue.Among those cited in the book are the Midrash (“It is man’s responsibility that he does not become ill”), Rabbi Bahya ibn Pakuda (“Not taking care of your body is equivalent to committing suicide”), the Hafetz Haim (“The entire Torah is dependent upon the mitzva of taking care of your body”), Rabbi Samson Raphael Hirsch (“A good spiritual life can be conducted only with a body that serves as an efficient instrument for that purpose”) and Rabbi Chaim Kanievsky (“It is biblically prohibited on yom tov as well as on any other day of the year for a Jew to smoke”).It seems that Am I My Body’s Keeper? is indicative of a greater awareness of proper exercise and nutrition among the faithful. A similar book, published in 2016, To Your Health: The Torah Way to a Healthy Life in Modern Times, also was written by a learned Israeli layman, Yechezkel Ishayek.Both books contain valuable, even lifesaving messages, but readers would be well advised to follow up by conducting their own research and consulting with well-informed experts for up-to-date and relevant information on diet and exercise for their individual needs.