While sitting in her lounge chair drinking beer and watching a ball game, Bertha Dribble decided to turn over a new leaf and get into shape. Bertha hollered out to her husband to go to the library and find her a book on physical fitness. When Mr. Dribble got to the library he saw a book with "How to Jog" on its spine. He took the book home. When Bertha finally glanced at the book several weeks later, she found that it had nothing to do with getting into shape. Why?