04/20/2013 09:42 am ET Updated Jun 20, 2013

Take Control of Your Fears, Take Control of Your Life

In the fall of 1998, I was medically retired from the Marine Corps. I was a Gunnery Sergeant, with almost 15 years of service. I had been a Marine since I was 17, and had planned on doing 30 years. But now all of that was over.

A cancer syndrome I have, called von Hippel Lindau (VHL), had progressed, resulting in four brain tumors and kidney cancer on both kidneys. That, when combined with the loss of my left eye due to the disease a few years earlier, added up to my career being over.

I was down, depressed, and confused. But, mainly I was scared. Being a Marine was all I'd wanted to do since I was a 10-year-old kid. What would I do now? And would the disease I have get even worse?

I guess I could have just gone home and taken it easy, as was recommended to me by most medical experts. They'd told me that my best years were far behind me; that I'd never be able to do the kind of things I once had.

But I chose to not listen to all of that. Instead, I rebuilt myself ‒- mentally, physically, and spiritually. I went on to become a world-class adventure athlete and have done things that even surprise me. And in the process, I have learned a lot about overcoming fear. Which brings me to Alcatraz prison.

Alcatraz is probably the most infamous of all prisons. There is an aura about it, the way it ominously sits out in the San Francisco Bay, surrounded by treacherous, ice-cold water, brimming with sea creatures. It's no wonder that supposedly no one ever escaped during its many years of existence as a federal prison.

But, I wanted to prove that it could be done. That if someone made it to the water, and knew what they were doing, they could, in fact, swim off the island to San Francisco. I would not only just swim it though; I'd do it with my hands and feet bound.

I taught water survival in the Marine Corps, and one of the things we'd do to show what is possible in survival scenarios is swim with our hands and feet tied, so I knew I could swim that way. Still, doing it in an open ocean environment, with who knows what looking up at me, had me scared.

Even though it ended up being one of the hardest things I've ever done, I was able to make it and am now one of only three people to have done the swim in such a way. And, while you may never do such a thing yourself, I know you have to deal with fear as well. The following tips help me face it; I hope they'll help you too.

Stop irrational thoughts. When in a fearful situation, the creative part of the brain takes over and begins to conjure up all sorts of dire thoughts. It's hard to think rationally in that state of mind, so it's vital you switch back to the logical side. To do so, try this: recite your ABCs backward, or count as high as you can by threes, or name all of the seven dwarves. All of these methods force you back to the logical side of the brain, allowing you to think rationally.

Evaluate the fear. Is what you're feeling real, or is it something you've simply made up? Some fears are legitimate and we need to be aware of them (like the fear of jumping into a fire) and respect them. However, it's usually the ones that aren't real, the ones that we simply make up, that hold us back the most in life. That's why it's important to know the difference.

Act accordingly. Once you've made your evaluation, act on the fear accordingly. There is a lot of power in the acting. Something verging on the supernatural happens. In fact, a famous saying says that by doing the thing you fear, the death of fear is certain. I have found that to be totally accurate.

Build your courage muscle. Just because you face a fear once doesn't mean that it goes away forever. The more you do so, however, the easier it is to deal with. A great goal to have is to do something to build your "courage muscle" each day. It doesn't have to be something physical, or dramatic, just something that takes you out of your comfort zone.

This post is part of a series produced by The Huffington Post as part of our continuing commitment to recognize fearlessness. To share your story of Becoming Fearless -- either your own or that of someone you know -- send a post (500-850 words), with your headshot and brief bio, to