Let's face it: For a long time sweat suffered from an image problem. Remember sweatshops, malaria, Richard Simmons' Sweatin' to the Oldies? But today, sweat sells. Take Hugh Jackman's damp undershirt, which went for $30,000 at an auction last December. Or the arresting images of Gatorade-colored droplets of perspiration rolling off the bodies of the world's most famous athletes. Or Kate Upton's glistening cleavage hawking patty melts for Carl's Jr.

Not only is sweat sexy, sweat is vital. You'd die without expelling this mix of mostly water and salt, which prevents overheating. And it's a really good thing if you sweat a lot. "It's men who are most in-shape who will sweat the most, and the most quickly, because their bodies are conditioned," says Neal Pire, a New York-based personal trainer and fellow of the American College of Sports Medicine.

When you work out, muscle contractions generate heat. If you exercise regularly, you're better able to cope, for two reasons: One, the volume of your blood­—the stuff that carries oxygen to exerted muscles—is 20 percent higher, and this provides the fluid for sweating. Two, you start sweating sooner, because your body has been programmed to recognize the need for cooling faster. (Also, the more efficient you become at sweating, the better you hold on to sodium, which prevents muscle cramping.) This, in turn, means you'll be able to work out longer.

"It's the reason why a sweaty body looks attractive to people," says Michael Bergeron, executive director of the National Institute for Athletic Health & Performance. "The image implies active, fit, tough, and resilient."

So now that you know that perspiring is good for you, and that you should be doing more of it, here's everything you need to know to do it the right way.

• • •

How to Sweat Better

Anatomy Of An Oversweater

Sauna vs. Steam Room vs. Sweat Lodge