Masturbation is a normal function at all ages to relieve sexual tension or simply as nature's way of teaching eye-hand coordination. No accurate statistics are available, of course, but it's been estimated that 90 to 95 percent of all men and perhaps 85 percent or more of all women masturbate or have done so. There is no evidence that masturbation is dangerous to a normal and healthy person. As for frequency, that depends on the individual. For many men, daily -- or twice daily -- masturbation puts no real strain on the body, while others may feel far less need or desire. As long as you don't experience discomfort and your normal sexual functioning with a partner doesn't suffer, chances are your rate isn't excessive. If there is a danger to masturbation, it's that it tends to condition a man to ejaculate quickly, which can cause problems when he's with a woman and wants to prolong her pleasure.