At 6-foot-4 and 220 pounds of muscle, it was hard to miss Mark Selbee. And his personality was even bigger, according to his friends.

“People hear that someone was a fighter, and they think it means they have an attitude and beat people up,” Atlanta fight promoter David Oblas told The Atlanta Journal-Constitution. “Everything about him broke the rules of fighting.”

Selbee was no longer competing at kickboxing, but the four-time International Kickboxing Federation champion was never far from the sport he loved. He continued to train and mentor younger fighters, making sure to leave himself time for his wife and three children. Selbee was with two of his children on a boating outing Saturday when he drowned, according to The Kansas City Star. He was 45.

Though he had recently moved his family to a Kansas City suburb to be closer to relatives, Selbee lived for more than a decade in the Atlanta area. Between 2002 and 2006, he won four IKF championships, once as an amateur and three times as a professional. Selbee also was a third-degree black belt in tae kwon do.

“He went as far in the sport of kickboxing as you can go,” Oblas said.

Selbee’s death shocked members of the fighting community and longtime friends, including Ultimate Fighting Championship legend Forrest Griffin, a native Georgian. Griffin, who now lives in Las Vegas, considered Selbee a mentor when the two had the chance to work out at the same gym.

“He was a little older and he had his life together,” Griffin told The AJC by phone. “He was a big brother and a mentor to a lot of us.”

Griffin and other fighters didn’t have to worry if they didn’t live in Atlanta. Selbee would offer his couch to his friends without a second thought. Selbee lived life at full speed, Griffin said.

In addition to his wife, Amy, Selbee is survived by three children, Easton, Ellie Brooke and Hudson. A fund-raising campaign for the family has been established on the site giveforward.com.

The IKF posted an online tribute to Selbee, listing his numerous titles along with photos of his accomplishments.

A celebration of life will be held Friday at 11 a.m. for Selbee in Leawood, Kansas.