Do you define yourself by what others say, or by who you say you are? Are the definitions created by what you feel inside, or by what you do on the outside?

At age 37, I had mastered the act of wife, mom and teacher. On top of that, while my friends barely made it to the gym three times a week, I was pushing myself physically five or six times a week. I was a classic gym-junkie doing aerobic classes, spin classes and grunts over the weights, but the one thing I wasntwas a runner.

I mean, I could run, but only if it wasnt too hot, too cold, too windyor more than 30 minutes. And while I never stopped trying, it never really felt right and was kept on the list of things that Im not.

My parents, though, were real runners. They were runners who ran because they could, not because the weather conditions were perfect or because they had nothing better to do. They were runners because they ran and not only did they run around the block, but often ran for hours, covering 20 miles during their training runs. The goal: 26.2 miles, to be exact. I didnt think much of it, until the fifth time I stood as a spectator for The New York City Marathon. There was my dad, cruising along at some speed clearly too fast for him at mile 16 (still smiling) and then my mom, some miles behind, just happy to hit the pavement slow and steady. It was that day, though, that I noticed the other runners as if for the first time. There were mothers, fathers, and friends running in packs. There were runners for a cause, and perhaps some looking for a cause, while others simply struggled to see a mile-marker somewhere in sight. There were old, young, skinny, overweight and even disabled runners, but no matter who they were, they all revealed one thing: their strength.

They had all endured 16 weeks of training, the pounding of the pavement, the silence of the streets and now shared a look of pain in their eyes as they reached mile 23. It was that look that made me wonder what gave people the strength to carry on, even when what they wanted to do was lie down. Who were they and who could I become if I could redefine myself as a runner?

And so, I began my quest to redefine myself. It was a huge challenge for me, but according to my mom, not as big as choosing just the right words for my shirt.

The shirt will make or break your run, she said confidently. Questioning the truth behind her words, I stared at my shirt in awe. U Go Girl! YOU GO GIRL! I said, feeling a little more hip than usual. It seemed crazy, but maybe there was something magical about those words. Perhaps I did have a real chance at becoming something I had not been before. On race day I felt focused and strong, unafraid of bridges, big cities, strangers, failure and stomachaches. My dad and I were, Go Mercury and You Go girl and that was how we would remain for the next 26.2 miles. You go!

Go Mercury! a stranger yelled. And then it came. You Go Girl!

At that, I turned to see a group of women yelling for me, as my blood rushed through my body. With an extra bounce in my step, I put my closed fist in the air as if to cheer myself on. This was clearly just the beginning as the crowds continued to chant our new names throughout the race, with their voices carrying me weightlessly through the air for ten miles.

After the next 13 miles, though, I was feeling quite heavy and wondered where the strength for 3 more miles would come. A dull ache began in my back and the arch of my foot seemed to be scraping on the pavement. I glanced at my husband, who had joined in for support and prayed he could read my mind.

Im tired, I said weakly, in case he didnt know.

Twenty-three miles might do that to you, he said with a slight laugh. You got this, he added with confidence. You go girl.

It was those three little words that transformed me in a matter of seconds, as if being handed a completely new title. I lifted my head high and began to hear the Central Park crowds roaring. The sensations from my body began to dissolve as I continued in stride, each stride lighter than the next, and each YOU GO GIRL giving me just the energy I needed. I looked carefully at each person that cheered for me, memorizing the smells and the sensations.

Im going to make it, I said to myself as I saw mile 26 approach. Im going to make it for sure. Tears welled up in my eyes as my fist continued to acknowledge the strangers who supported my new name and then I saw the finish. You Go Girl! someone yelled.

Im going! I yelled back. With the finish line in sight, my dad grabbed my hand. I could feel his strength, as well as my own as our feet crossed the line in unison and we smiled from ear to ear.

This was not just about finishing or about reaching a goal. It was about crossing the line in my own life and finding out who I could truly become. The list of possibilities now seemed endless and I couldnt help but cry. You Go Girl!