Masturbation is a healthy and normal practice, like daydreaming or napping. Even masturbating several times each day is completely harmless. You may encounter people, books, or websites that say masturbation is bad or harmful; this is just plain incorrect. As any reputable medical doctor will tell you, old myths about masturbation affecting the eyesight, causing permanent fatigue or insanity, etc., have long been disproved. In fact, recent studies suggest that ejaculating regularly isn't just fun, it can actually help prevent a certain kind of cancer later in life.