Gilbert Gaona trained for his first marathon in Fallujah, Iraq. The process didn’t start with any goal in mind: Gaona and his fellow Marines started running around their base to exercise and blow off some steam. There aren’t many ways to clear your mind in the middle of a war zone. The runner’s high became a godsend.

Then it became a lifestyle, at least for Gaona. His first marathon was the 2006 Rock ‘n’ Roll San Diego Marathon, and he’s run in 22 since, including Boston. This Sunday, Gaona will participate in the 50th running of the New York City Marathon, along with 177 other members of the city’s popular LGBTQ running and triathlon club, Front Runners New York.

For Gaona, there’s nothing quite like getting out there and letting the endorphins run wild.

“Running is my routine and metal state,” he said. “No matter where I go in the world, I am able to take running with me. I can literally run toward goals and run away from problems, even if for just a moment. I always feel better after a run than before.”

Gaona (left) has made lifelong friends on the pavemen, including his fiancée, Jesus Martinez.

It took years for Gaona to find mental peace with his sexuality, and running played a big role in his journey. With “Don’t ask, Don’t tell” in place, Gaona didn't have to think about his sexuality while he was in the Marines. Part of Gaona’s motivation for joining the armed forces was the ability to suppress his gay thoughts and feelings.

“Being in the military was a way to not have to come out,” he said. “I also honestly never thought I would come out, because I didn’t want to be gay.”

Interestingly enough, Gaona befriended many gay men after his stint in the Marines, despite the apprehension he was feeling about his own sexuality. He was San Diego’s No. 1 gay ally.

That actually made joining the gang a little bit harder.

“I surrounded myself around more and more gay friends until finally I started coming out,” he said. “It was actually really difficult to come out to my gay friends, because I had built such a friendship as their straight ally.”

Gaona made the decision to tell everyone when he was — you guessed it — on a run. Then he dashed to Google and searched for gay running clubs in San Diego. That led him to the Front Runners.

“It was a fresh start for me,” Gaona said.

Three years later, Gaona met his fiancée, and now they live in NYC — one of this world’s great gay meccas. As president of FRNY, Gaona is fully immersed in the city’s gay sports scene.

In running, they often say the first mile is the hardest. The same aphorism applies to Gaona’s coming-out journey.

“For most my runs, no matter the distance, the most difficult part is the first step — making that decision to go,” Gaona said. “From there, it is just one foot in front of the other.”

That will be Gaona’s mantra Sunday. Those are pretty good words to live by — marathoner or not.