It's almost always unspoken. It's almost always unacknowledged. But it's there, in just about every workplace. It's the four-letter F-word that paralyzes people and organizations. It's F-E-A-R. Fear of change. Fear of losing control. Fear that something you've created - an idea, a plan, a product - will be shot down.

How can we get over the things that scare us, and break out of that deer-in-the-headlights trance? FDR uttered the famous line "The only thing we have to fear is fear itself," but it was Eleanor Roosevelt who offered a prescription for overcoming fear: You must "look fear in the face. . . . You must do the thing you think you cannot do."

Recently I put her advice to the test. I looked into the cold, unblinking eye of a seven-foot Caribbean reef shark while about 30 other sharks circled all around me. And I discovered, 35 feet underwater, that sometimes fear is good. Because if you're never scared, you never take chances.

"When a man knows he is to be hanged in a fortnight, it concentrates his mind wonderfully." - Samuel Johnson, 18th-century English essayist and poet

I've stopped telling friends that in two weeks I'll be diving among sharks. Their reactions have been less than encouraging.

"Isn't that, ah, awfully dangerous?" inquires one buddy, a marketing VP.

"You'll be inside a cage, right?" asks another, an editor.

And from my attorney: "Sounds like a death wish to me."

I just smile and explain that sharks are essentially shy and that a cage won't be necessary. According to everything I know about dangerous animals, I'm far more likely to be attacked by a domestic pig than by a shark. Jaws made us silly on the subject, I tell my friends, by depicting every sleek, stiff-dorsaled creature as a demonic eating machine. My friends remain silent, but I can tell they're unconvinced.

To reassure myself, I call up Dr. John McCosker, senior scientist at the California Academy of Sciences. McCosker, a renowned ichthyologist, has co authored a book with Richard Ellis on the most dangerous of the breed (Great White Shark, Stanford University Press, 1991). He sets me straight.

"Sharks have a lot more to fear from us than we do from them," he says. Worldwide, they've been overfished for their fins and meat, and for sport, and they've been terrorized by humans made stupid by fear. But of the 369 species of shark, just three - the great white, the bull, and the tiger - have attacked people without provocation, and even then, only on rare occasions.

I lodge all this comforting information safely inside my brain. But in my amygdala, the part of the brain that relates to our most basic survival mechanisms, I'm replaying the theme from Jaws.

I admit it: I'm scared by the prospect of slipping into the ocean and getting bumped a couple of notches down the food chain by a creature more merciless than a CFO.

As I pack for my rendezvous with dorsal-finned destiny, I tell myself that I'm the genetic victim of the flight-or-fight syndrome. We battle fear with great explosions of adrenaline, or we run from it. That was a useful reaction when we lived in caves. But today a more rational response is required. I figure that if I can use my scuba-diving skills to exorcise the most basic fear of all - that of being eaten - I can cope with most anything.