(CNN) -- At age 16, Rob McCullough walked into an LA Boxing gym for the first time. The teen had left home, moving from one friend's couch to another, and now finally felt like he found a place where he belonged.
"I went to the gym and worked out, and worked out my stuff," he says. "That was kind of my safe haven."
After taking his first class and leaving with a compliment from the instructor, McCullough was hooked. "It built self-confidence," he recalls. "At the end of the day, I felt great about it."
Life was difficult at times for McCullough and his seven siblings who were raised by a single mother. Constantly relocating, he remembers how other kids were not always welcoming when the family moved to a new neighborhood. "I dealt with bullying growing up as a kid because I was always the new guy at the school," he says.
By the time he reached high school, a new challenge would shape his future.
"Going to a school with a lot of gangs at one point was kind of one of the things that got me to start and think, 'If I learned how to fight really well, people won't want to bother me at all,' " he says.
McCullough, known to his fans as "the Razor," didn't just learn to fight. He went on to become a World Extreme Cagefighting and five-time United World Muay Thai Association champion, making a successful career taking down opponents in the ring.
From a childhood with such challenges, McCullough found both a passion and an occupation. "I found sports. I found mixed martial arts; it was like therapy," he says.
Now McCullough, together with LA Boxing, said he wants other children who face bullying to have the same opportunity. "I would like to share with other kids that maybe if they are going through issues of being bullied, or they are a bully, it's a place that they can go to to work that stuff out," he says.
Through the anti-bullying campaign, McCullough said he is sending a message to kids. "We are going to schools in neighboring areas that we have gyms, so that these kids know there is a safe haven that they can go to." The campaign reaches out to children by holding interactive assemblies at schools nationwide, promoting gyms as a positive resource for building self-confidence.
He isn't doing it alone. Big names in the martial arts arena, such as Ultimate Fighting Championship President Dana White and former light heavyweight champion Tito Ortiz, have joined in to help stop bullying and promote their sport.
"We are guys that fight for a living, and we could obviously be mistaken for bullies, but we are nothing of the sort," McCullough says.
"We fight for many reasons, but we don't fight to be bullies."
For some of these fighters, the struggle with bullying is personal. "I have interesting stories from guys that are current active fighters," McCullough says. " I had one guy say, 'I would love to be a part of this campaign because I used to stutter and I got made fun of all through high school.' "
McCullough now has another reason to get involved. "I have a 2-year-old son, and I started to think about it," he says. "What if my kid gets picked on?"
Martial arts may not appeal to all the children in the campaign's assemblies, but McCullough said he is sure the message is true for everyone. "I think at the end of the day it's respect," he says.
"Sports did it for me, and it did it for a lot of my friends that are professional athletes. It gives you something to focus on."