Many women are having sex these days not because they enjoy it but because they feel they have to. A new survey finds that while most women are happy in their relationships, a lot do not factor sex into this happiness. Though 42 percent of women who participated in the survey said they believe sex is a key factor in their health, the frequency with which they have sex does not reflect this—but maybe it would if they knew some of the real benefits of sex. The study also found that women who have sex at least four times a week look as much as 10 years younger than they actually are. “While pleasure and intimacy with your partner should be a primary motivation to have sex, the health and wellness benefits are a big bonus,” said one of the psychiatrists specializing in women's health who was involved in the research.