Editor's note: Sia Figiel is one of six CNN viewers selected to be a part of the Fit Nation Triathlon Challenge program. Follow the "Sassy Six" on Twitter and Facebook as they train to race the Nautica Malibu Triathlon with Dr. Sanjay Gupta on September 14.
(CNN) -- At 400 pounds I had little self-confidence. I measured my value not by my abilities but by the number of pounds on a scale.
No matter how reassuring friends, family and co-workers were, I saw myself as a failure because I couldn't manage my weight or my diabetes.
After a move to the U.S. mainland from American Samoa almost two years ago, I picked up walking and swimming, and started eating more fruits and vegetables. I avoided anything that came in a can or a box.
As the weight came off slowly, I started believing in myself -- and in my ability to turn my life around.
After our first Fit Nation meeting in Atlanta, I committed to walking in the mornings and training in the evenings. My walking partner would pick me up at 7 a.m. daily, and we would go to Tampa's MacDill Park, where we walked two miles.
Every morning we saw a girl running nearby, and we would marvel at her speed and form. She ran with such grace.
"One day," my friend told me, "you're going to be running just like her, mi amiga!"
There was passion in her voice when she said it -- a passion that meant she believed in me. But I found it hard to believe it myself. After all, the runner was smaller. Much smaller. And there wasn't an ounce of fat on her body.
Up until that point I was walking for five minutes and then jogging for a minute. That minute felt like an eternity. Before I even got to the 30-second mark, I would be gasping for air.
But each morning I saw the runner, I felt inspired. I knew I needed to put more effort into my workouts. Each week I added another 15 seconds to that minute until finally, three weeks later, I decided to give it a shot and run two consecutive minutes.
To my surprise, I kept running long after the two minutes were over -- until I realized I had run my first mile nonstop.
Two weeks later, I ran four miles nonstop in a time of 1:04. I remember being so excited and needing to tell someone. But my sons didn't quite get it when I rushed through the door, breathless, and told them I had just run nonstop for an hour. All they said was, "Cool, Mom, what's for breakfast?"
In the past, this lack of encouragement would have stopped me. But I've since realized I don't need to be reassured by anyone. There's something that happens once you chose to believe in yourself; out of nowhere, you'll sprout wings you never knew you had.
Each Saturday since, I've been running for four miles. Last Saturday I ran my best time of 57:55, with one of my laps at 13:27.
My goal is to run a 10-minute mile.
Beating my own time is my newest joy. It is a rush that keeps me going daily.
There's nothing like hearing my sons complain when we're walking to school in the mornings. "You're always running, Mom. Why can't we just walk?"
I may not be the most graceful runner on Saturday mornings, but I'll keep going till I get to my goal.
I've learned that you don't have to be thin to run. You just have to believe that you can.
Only this time, I've forgotten to be afraid.