We all race for a reason - this is mine

Editor's note: Denise Castelli is one of seven CNN readers chosen to be a part of the CNN Fit Nation Triathlon Challenge. She lost her leg to an infection following a tragic accident in a collegiate softball game.

There are moments in all of our lives when we need to stop what we're doing, take a second, look around, and soak it all in.

For me, this happened multiple times while I was training in Hawaii with the "Lucky 7." The Big Island was beyond what any words can describe and spending so much time with my teammates was unforgettable.

I learned a lot on this trip, but one thing in particular sticks out.

What I learned about triathlons during our Kona training trip was life changing. Sure, I learned technical things - like how to transition and swim more efficiently in the open water. But it's so much more than that. During this trip, right on the Queen K Highway, I learned how to release.

Ever since my amputation, I've taught myself to bottle up my emotions and to completely forget that they even exist. Sometimes when I'm alone, I'll have brief, fleeting moments where I'm reminded of what I went through and I immediately shut it down.

Not only are the memories painful, but I never saw the point in reliving all those dreadful months I spent in the hospital. Bottling everything up and stowing it away on an internal shelf somehow seemed more effective in getting on with my life. This philosophy has "worked" for me for years. I never thought a training trip to Hawaii would upend that.

If you've been to Kona and you're a triathlete, you already know all about the Queen K Highway and all her glory.

It's essentially the bike route for the Ironman World Championship, and this week I learned exactly the reason why. Not only are you riding next to hot fields of lava and cars traveling at high speeds, but the hills can be difficult to navigate ESPECIALLY with the infamous Kona head winds blowing you around on your bike. It makes climbing the hills dreadful. The wind was so bad that even when we approached a downhill or a flat part, it still felt like we were on an incline because of how much resistance we felt and how hard we still had to peddle.

We were in the middle of our 28-mile ride to the center of Kona when I began breaking down. Coach April and I had approached yet another tough hill, and all my energy was put into my peddling. For some reason, this made me drop my guard, and all those emotions that I had bottled up inside began to come out.

I was crying hysterically all the way to the top of the hill - not because I was hurt or because I was tired; there really was no explanation. Coach April asked me what was wrong and all I could do was nod my head.

She did her best to console me but how could she help me solve a problem when I didn't even know what that problem was? Everything hit me at once like a ton of bricks.

After the ride, I began to mentally dissect what happened to me. What was it about that climb that brought on all of those painful memories? And then, it came to me.

My entire life, everything was easy for me. I always seemed to be a "natural" at the things that I tried. I could play Chopin on the piano, steal second base safely 95% of the time, bowl a 279, maintain a 3.5 GPA with minimal effort - I was ALWAYS coasting downhill.

Sure, I had pushed myself a lot while I was an NCAA athlete, but nothing can compare to the amount of training I am doing for Malibu. Nothing.

I realized that after my amputation, my life had become an uphill battle. Unfortunately, there is no coasting when it comes to wearing a prosthetic. It's something I have to do day in and day out; there is NO other option. And while that can be overwhelming at times, learning to metaphorically climb the hills of my life has made me a better person - just as physically climbing hills has made me a better athlete.

Having to face all these emotions isn't something I wanted to do, nor was it something I was ready to do. But it was something I had to do. I'm thankful that I've found my new release in life: triathlon. We all race for a reason, and this is mine.