“The brave man is not the one who has no fear, he is the one who triumphs over his fear.”

— Nelson Mandela

My friend Kamal is a world traveler. He has meditated with Tibetan monks in the Dalai Lama’s monastery, trekked the Himalayas, and hiked the Camino Real in Spain. He served in the U.S. Army and studied to be an ER doctor. He has launched tech companies, runs his own venture capital firm, and is a bestselling author. Up close, he makes quite the striking impression with his flowing mane of silver hair, quiet voice behind a steely gaze, and the super-calm demeanor of a Buddhist master. Here is a guy with all the ingredients for success on a mega scale. But I recently learned a secret about Kamal.

He couldn’t swim.

At first, I had a hard time believing it. I thought he had to be exaggerating. To me, swimming comes as naturally as breathing. I grew up on and in the water. My family lived for years on a sailboat. I spent more than a decade in the navy, trained, and deployed as a U.S. Navy SEAL. The idea of not knowing how to swim was beyond my comprehension. But here was my friend, this amazing, talented guy who had accomplished so much in his life… and he couldn’t swim.

I gave him kind of a hard time about it. I pointed out that the human body is more than 60 percent water. Did he realize he was already floating around inside his own skin? I wondered aloud if, when his parents conceived him, the egg cell had to swim down to meet the sperm cells, instead of the other way around.

“Dude,” I said, “how can you possibly not know how to swim?”

'Mastering Fear: A Navy SEAL's Guide' by Brandon Webb and John David Mann -- Fear of the Water

Read Next: 'Mastering Fear: A Navy SEAL's Guide' by Brandon Webb and John David Mann -- Fear of the Water

The answer was simple.

Fear.

Kamal told me that he had been terrified of water his whole life. A few times, when he was living in the Dominican Republic, he went kite surfing. He always wore a life jacket, but that didn’t make any difference. He was still terrified. What would happen if he fell and hit the water? He told me stories about being out at his buddy’s Tim Ferriss’s house in the Hamptons. Tim has a big beautiful pool in his backyard where people hang out, swim, and have a fantastic time. Kamal felt awful that he could never join in.

Kamal, I realized, hated the fact that he couldn’t swim. And it wasn’t as if he’d never tried to learn. He’d taken courses and studied online workshops. For a while, he lived in a building in San Francisco with the only heated outdoor Olympic pool in the city, and he brought in a private instructor. That hadn’t worked, either. No matter what the various teachers tried, he couldn’t handle the feeling of his feet not touching the bottom, and he would quickly reach the point of panic. Now he was thinking about doing one of those immersion courses in Florida. Or so he said. But I noticed he kept putting it off.

I stopped giving him a hard time about it.

Instead, I decided to do something.

I had a week coming up at home in New York with no trips scheduled. “Look,” I said, “you give me a commitment for a week, and I’ll teach you myself. But you have to commit to meet me, every day at the same time, rain or shine. Give me a week, and I’ll have you swimming.”

“Okay,” he replied.

'Mastering Fear: A Navy SEAL’s Guide' by Brandon Webb and John David Mann — A one week commitment

Read Next: 'Mastering Fear: A Navy SEAL’s Guide' by Brandon Webb and John David Mann — A one week commitment

On the appointed morning, I went into the New York Athletic Club, right off Central Park South, headed upstairs to the pool, found a free lane, and slipped into the water. I got there a little early so I could take some laps while I waited for Kamal. As I schussed silently through the water, my thoughts slipstreamed back two decades.

Summer of 1995. It’s nighttime over the Persian Gulf. The four of us — pilot, copilot, another crewman, and me —have been out in our H-60 Seahawk helicopter doing sonar ops. It’s been a long night, and we need to refuel on a nearby destroyer before heading back to the aircraft carrier we’re calling home.

The pilot slows us down to a crawl as we approach the vessel below. Landing on a destroyer’s deck is always tricky, more so on this moonless night. Someone needs to spot the deck as we hover in place high above the ship and talk the pilot down. Tonight, the spotter, the guy strapped into the gunner’s seat down in the belly of the bird, is me.

I crack open the door and look down, scanning for telltale lights. There aren’t any. That’s weird. I glance upward —and now I see lights. What? For the span of a single breath, I experience total disorientation. Why are there lights up here at eye level when the destroyer is way down below us? Then the disorientation evaporates as I look down again and see water, right there at my feet. Persian Gulf water — churning, grinning, reaching up for me, curling around my ankles.

Oh, shit.

We’re not hovering high above the ship after all. Our goddam pilot has put us right down in the drink. Seawater is pouring into the cabin, caressing my legs, climbing the interior walls, searching for the engine. “Hey, baby. I’m here. Come to papa.” This is so not good. If the engine chokes and dies, we flip upside down and sink straight to the bottom of the Gulf.

“Altitude!” I shout into my comms. “Altitude!”

And here’s where it really starts to get fun. Because our pilot, the guy in charge of this operation, the guy who’s supposed to be our leader, is now seized by full-on panic — and he freezes. “What’s happening?” he screams as he takes exactly zero corrective action. “Oh God, oh God, oh God…!!” This is not what you want to hear from your helicopter commander in a moment like this. Fear has paralyzed him, taken him, swallowed him whole.

And because of that, all four of us are going to die, right here, right now.

I finished my laps and pulled myself back up onto the pool’s edge to wait for my friend.

I knew what it was that had Kamal in its grip. And I knew why all those other teachers who’d tried to help him had failed. They thought they were supposed to teach him how to swim. They were wrong. This wasn’t about learning how to swim.

It was about learning how to harness fear.

During SEAL training there’s a pool competency phase in which the instructors do everything they can to freak you out. They send you down with an oxygen tank and then tie your air hose in knots so it doesn’t work, anything to throw you into a panic, and then see if you can find your way out. You sit there, waiting for your turn with your back to the pool, and listen to the classmate ahead of you in the water, thrashing, and drowning. It never got to me, but it sure terrified the living crap out of quite a few classmates. And I could understand why. I might not be afraid of the water normally, but I just about shit my pants that night over the Gulf.

We didn’t die, though, because of one reason. Our copilot, Kennedy, knew how to harness fear. He ignored our useless gibbering pilot and commandeered the controls himself, pulling us up out of the water and planting us safely on the destroyer’s deck. To this day I don’t know how he did it. It should have been impossible. (The maintenance chief thought we were making the whole thing up until his crew undid the tail section and 10 gallons of seawater poured out.) But fear like that will let you do impossible things — if you know how to channel it.

Kennedy knew how to channel it, and it’s a good thing he did. If he hadn’t, you wouldn’t be reading these pages.

As I said, I grew up on the water. Love it, spent my childhood in it, and a good chunk of my adulthood, too. But there’s a reason people use water when they want to drive you to the edge of sanity and break your spirit. If I say, “I’m going to drape a cloth over your mouth and soak it with water,” that doesn’t sound too bad, does it? Oh, but it is. It can push strong-willed men right over the edge. In my military training, I got familiar with the process of waterboarding: in essence, you are slowly, methodically being drowned to death, engulfed by water. There is something primal about the terror this creates.

When I was a kid, I saw a girl drown because of someone’s carelessness. I was there when they brought her body up and laid her out on the deck, statue-still, never to take another breath. It was the first time I’d seen death, up close, ugly, and personal. I’ll never forget it.

Kamal couldn’t handle not being able to touch bottom in a 10-foot pool. I got that. I don’t how many feet deep the Persian Gulf was that night, but if our copilot hadn’t kept his composure I would have found out.

Yes, I understood why my friend was afraid.

A few minutes later, Kamal showed up. Right on time. We sat at the pool’s edge, our legs in the water. I pushed off and slipped down under. He followed, lowering himself in slow and tense, hands gripping the lip of the wall. He’d never been in a 10-foot depth before. “I’m in,” he murmured, but his body language was screaming, “and there’s no way in hell I’m letting go of this wall!”

We got to work.

That first day I kept things light. Nice and easy; almost too easy.

The second day we repeated everything we did the first day and went a little further.

The third day he did 10 laps on his back.

“You’re swimming, man,” I told him. He was startled to realize that it was true.

On day four, instead of sitting down poolside and carefully slipping into the water, he went running to the edge, launched himself in the air, and landed in the pool in a humongous cannonball. Huge splash, water everywhere — and then Kamal’s face bobbing up in the middle of it, grinning like a kid.

He had never done a cannonball before in his life.

And that’s how every lesson started for the rest of the week: Kamal running to the edge, jumping off, and doing a giant cannonball into the pool, then surfacing with that Cheshire Cat grin. A big, grownup, silver-haired kid. I’d never seen anyone so happy in my life.

On that third day, the day he did 10 laps on his back, we had an interesting conversation at the end of the lesson.

“You know, other people have tried to teach me,” he said, “but it never took off. They would get me in the water, demonstrate a stroke, and then get impatient when I couldn’t do it. They would get frustrated and say, ‘it’s so easy, man, just try it.’ But I couldn’t ‘just try it.’ I was too terrified.” He looked out across the pool.

“Until now,” I said.

Still looking at the water, he nodded. “Yeah. Until now.” Then he looked back at me and said, “You need to write a book about this.”

So I did.

You can check out Mastering Fear to read the full tale. The book is helping people in over half a dozen languages.