When it comes to sex, men are expected to perform immediately and often. This is clearly an oversimplification of male sexuality but many of us can't help but give it some credibility. These expectations can make any sexual functioning issues much scarier and embarrassing than they need to be — or "one of the most debilitating experiences for most men," says Stanley Ducharme, a clinical psychologist affiliated with Boston Medical Center and Boston University School of Medicine. With the pressures put on men concerning their abilities, even a single incident can lead to long-term anxiety. Here's how to fight it.