Copyright © 2021 by William J. Pierce, EdD, and M. Scott Murr, EdD
Copyright © 2007, 2012 by William J. Pierce, EdD, M. Scott Murr, EdD, and Raymond Moss, PhD
All rights reserved.
Published in the United States by Rodale Books, an imprint of Random House, a division of Penguin Random House LLC, New York.
RODALE and the Plant colophon are registered trademarks of Penguin Random House LLC.
RUNNER’S WORLD is a registered trademark of Hearst, Inc.
Earlier editions of this work were published in 2007 and 2012 by Rodale, an imprint of Random House, a division of Penguin Random House LLC.
Library of Congress Cataloging-in-Publication Data is available upon request.
ISBN 9780593232231
Ebook ISBN 9780593232248
Photographs by Jeremy Fleming
Cover design by Pete Garceau
Cover photograph by vernonwiley/E+/Getty Images
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