Big-wave surfers thrive off fear, training the complex circuits in their brains to work properly in high-stress scenarios like this. Photo: Glaser

A few winters ago, I got amped on surfing Mavericks. I'd never been all that keen on waves that might end my life, but my girlfriend had dumped me and I was looking for something to re-inflate my ego. Nothing like bombing down a 20-footer with a 10-foot stick between your legs to make you feel like a worthwhile human again.

So I walked to Danny Hess' shaping shack near San Francisco's Ocean Beach to show him my dragon slayer: a 9'0" rounded-pin, about 20 inches wide with 2 ¾-inch rails. Danny makes gorgeous Mavs guns and surfs the place upward of 40 days per season. He always seems über calm about it, which made what he told me next all the more frightening. "I can't let you paddle out there on this board," he said. "This is not a Mavs gun."

What? My 9'0" had seen me through the most epic days of my life, yet here was Danny telling me that Mavericks was going to make my slayer feel more like a broom stick. "I've been beaten so badly out there," he said, shaking his head, "it's not a place to experiment."

"How do you deal with the fear?" I asked.

"People call it Mav-siety," Danny said. "Sometimes you can't sleep before a swell. But you find yourself going anyway. We're probably all sick."

I felt sick. And I didn't go to Mavericks to see for myself. Not that season. Too scared. But Danny sparked my curiosity.  How did anyone deal with the fear of a potentially deadly wave?

I tend to geek out about questions like this and I spent the next year interviewing neuroscientists, psychologists, and a handful of the core Mavs crew about how fear works in our brains. The science of fear turns out to be ridiculously complicated. In fact, I proceeded to write an entire book about it, The Fear Project, and barely scratched the surface. But you have to start somewhere, and there are some fascinating basics that start to explain how people like Danny do what they do.

To understand fear, you have to understand a little about its manufacturing hub: your brain.  It turns out you have a lizard and a rocket scientist in there. The lizard is the most ancient part—literally hundreds of millions of years old—deep down near the top of your spinal chord. This is where your instincts and emotions largely stem from. A little almond-shaped gizmo within that lizard brain called the amygdala is often dubbed your "fear center" because it tells your body to pump out adrenaline and cortisol (a stress hormone), giving you the feeling of being amped, scared, or—as is usually the case in big-wave surfing—both.

The rocket scientist is your pre-frontal cortex, near your forehead. It's the part of you that, more or less, makes you human. Other mammals have a pre-frontal cortex too, but ours got really damn big and allows us to plan for the future, make origami, split atoms, and build surfboards.

The cortex is nifty. But the lizard is the Jedi. It's fast, so fast, you don't notice it work. Think about the last time your friend startled you. You jumped before you had time to think of who it might be. Because of its speed and heightened intuition, the lizard can be amazingly helpful in surfing. It might allow you to dodge some 10-foot gun screaming toward your head before the rocket scientist even notices, "Oh crap, a surfboard is going to decapitate me." That said, the lizard can be very bad for surfing. At Mavericks, fear might make you literally freeze up at the crest—the deer-in-the-headlights syndrome—instead of ditching your board and diving into the pocket. (Ask Jacob Trette, the surfer who nearly drowned at Mavs in 2011, why the latter might be a better option.)

Fear also makes a lot of athletes underperform, which is why so many pros don't surf to their potential in contests. That's not actually the lizard's fault. The lizard's super-fast fear response can trigger the rocket scientist into worrying and trying to over-control an already ingrained movement. You don't "think" about doing a cutback; you just do it. But fear can make you second-guess what your muscle memory already knows, try too hard, and suddenly the cutback looks silly—a choke.

A lot of life is our lizard brain reacting super fast to life's many varied waves and the rocket scientist trying to interpret the data. But it also works the other way around. Your rocket scientist can dream up situations that route to your lizard brain and then to your body. I could sit here and merely think about Scarlet Johansson and get, um, stoked. Or I could sit and think about 50-foot Mavericks and give myself diarrhea—literally. Fear actually shuts down your immune system, sex drive, and your digestion because your brain is telling your body to get ready to use all that energy for survival. No point wasting energy producing sperm if there's not going to be a future, goes evolution's logic.

So, how does understanding this help with surfing? Far too many ways to mention here, but to start, you can train your rocket scientist to manage your lizard and paddle the hell out.

When Danny Hess first paddled out at Mavericks, he was terrified. But he reasoned that if he made himself do it on a relatively small day (meaning, still big enough to crush your house), he'd push through the fear. "I got caught inside," he told me, "went over the falls, caught a few waves, the whole bit, and I realized, ok, this is heavy, but it's not impossible."

For survival reasons, our lizard brain actually prioritizes our bad memories of Mavericks (killer of Mark Foo and Sion Milosky) over the benign ones (99 percent of waves are ridden without incident), a concept psychologists call negativity bias. So Danny's logic was a perfect example of the rocket scientist winning over the lizard's negativity bias. He was scared—and of course had Foo on the brain—but rather than trusting his gut that was saying, "Get the hell out of here now!" he reasoned that he had trained enough and that he could push through the knots in his stomach.

It worked. And amazingly, we can actually watch this happen inside the brain now. In 2010, a group of neuroscientists in Israel, led by Uri Nili (a rock climber), put snake phobics in an fMRI tube where they could watch different parts of their brains light up. Above the subjects, in a little window, was their worst nightmare—a live, writhing snake. Using a lever, the subjects could choose to bring the snake closer to their faces or farther away. When they were able to be brave and approach—much like Danny paddling out that first day at Mavs—a part of the brain between the eyes called the sgACC, where the rocket scientist lives, activated, seemingly "talking to" the amygdala.

The scientists also logged the subjects' responses by measuring sweat on their skin (a fear response) and interviewing them afterward. Some of them said they felt afraid, but hadn't actually shown much sweat response. Others said they didn't feel afraid but they had sweat a lot. Both these groups were able to bring the snake closer. It was the people who said they felt afraid and sweat a lot who succumbed to their fear.

What the study suggests is that at least two techniques work for being courageous in the face of fear, and they both include a near disassociation of the modern and ancient brain. In one scenario, the rocket scientist simply ignores the lizard screaming "danger," essentially plugging his ears and singing, "Lalala I can't hear you." In the other scenario, the rocket scientist seems to be able to actually tamp down the lizard's fear response, saying, "Yes, it's scary, but you better calm down because I'm going to drop in on this 40-foot wall of water anyway."

The cool thing is that the brain is highly plastic, or malleable, and everything you do actually changes its form, its synaptic connections. If Nili is right and this sgACC behind the eyes is the courage center, the more we exercise it, the stronger it gets, which is likely why Danny is now so calm about even the biggest swells at Mavericks. Sure, he's physically fit. But so is his brain.

Sounds simple enough, right? Approach your fears and you can debunk them. But not so fast. If Danny hadn't trained his whole life, slowly surfing incrementally bigger waves before Mavericks, he might have paddled out there and gotten badly injured (or worse), and that would have likely made him more scared of Mavericks. It's one thing to approach a fear like asking that gorgeous girl out on a date. You can crash and burn as many times as you want and recover.  When it comes to truly dangerous acts, creating positive experiences in baby steps is the key.

When Danny told me that my 9'0" wouldn't cut it at Mavericks, he loaned me his 10'2"—nearly 4 inches thick—and told me to practice on it at our home break before venturing out on any real dragon-slaying missions. I did. That advice may have saved my life.