Larry McCallon is 86 years old, but don’t tell the group of 13-year-old boys clustered around his table. Sure, they see him as an adult; after all, they respectfully call him “Mr. Larry.” But deep down, he’s one of them and so much more — friend, spiritual mentor, confidant, co-conspirator and jokester.

His laughter is just as loud (if not louder) as the young teens when recounting the previous night’s shenanigans. Older boys migrate to the table to join the fun. This group of missionary kids see each other at best, once a year, during meetings for International Mission Board (IMB) missionary families serving European peoples around the world. They can’t remember a meeting without Mr. Larry.

The short-term mission volunteer from California hasn’t missed one since 2003. He’s volunteered at 52 IMB meetings — general, missionary kid camps and marriage retreats. In all, he’s taken 107 short-term mission trips to more than 30 countries since retiring. Even though he has worked alongside IMB teams preaching, doing human needs projects and evangelism, his favorite mission trips involve missionary kids. In fact, he’s accrued over 1 million frequent flyer miles just from flights to minister to IMB youth.

“I get to see them grow up physically, spiritually and mentally,” Mr. Larry says about the 20-plus years of attending multiple meetings a year. “The consistency in working with youth is important. They know you’re going to be there, and as a result, they are willing to talk to you and open up about what’s going on in their life.”

Mr. Larry found his place with the 13-year-olds by accident. He had just returned from his first mission trip to the 2002 World Cup in South Kore when his church, Immanuel Baptist Church in Highlands, California, announced they needed help at a missionary meeting in Europe. Mr. Larry, the town’s mayor at the time, raised his hand. He reasoned that he was retired and had time to do whatever was needed.

The youth minister puzzled over what to do with a 63-year-old in a youth department of students growing up in many different countries and cultures. He decided these young teenagers might need a grandfather figure, since missionary kids aren’t always around their grandparents. Mr. Larry joined other adults to lead the youth. He taught the 13-year-old boys’ class at the meeting and never gave it up.

One IMB missionary who serves in Asia remembers watching Mr. Larry’s “grandfatherly” influence on the boys that first meeting. The teens flocked to him, soaking in the attention of an adult who was not their own parent. He teased, mentored and loved as only a grandfather can. After the meeting, the Californian kept in touch with the missionary families. He came back the next year to a new group of 13-year-olds while still interacting with the previous class.

“Larry loves our MKs (missionary kids). He not only poured out his resources but has poured out his heart,” the missionary said. His own sons were part of Mr. Larry’s classes. The family grew so close with the Californian through the years that he attended their weddings. “He’s been a constant in our lives since that first meeting.”

Investing in missionary kids and their families like this is one way Mr. Larry supports the IMB’s work of reaching the nations with the gospel. In his experience, teens have the same basic problems and issues no matter where they grow up. Some struggle. Some don’t. Some follow Jesus closely. Some don’t. Having parents in ministry doesn’t mean easier teen years.

“It’s cheaper to take care of the youth than it is to have families leave the mission field and bring a new (missionary) unit to replace them,” he explains, noting how important the meetings, retreats and camps are for this age group. It allows missionary kids to have a church camp or discipleship experience similar to their American counterparts.

“A lot of missionaries leave the field when their kids become teenagers for various reasons. This is what motivates me to come back,” Mr. Larry adds. “You never know what’s going to be that little difference in a teen’s life.”

For missionary kid Sawyer Harrington, the difference was about more than having someone easy to talk to about life issues. In a missionary kid world where people constantly come and go, the big difference is someone remembering him. Even though months and years pass, he can count on Mr. Larry clearly remembering him and his interests.

“He knows hundreds, if not thousands, of people, yet he still knows and cares about each of us on a personal level,” Harrington says. “His happiness at watching others succeed speaks volumes.”

Some of Mr. Larry’s former 13-year-olds are back on the mission field now as adults. Others are pastors, engineers and teachers. Each year, parents stop by his breakfast table to give family updates and thank Mr. Larry for his lasting influence. Some facetime their sons right there so they can catch up with their old mentor.

Breakfast is about the only time missionaries see the Californian at any given meeting. Nathan Pinkston, missionary kid, explains that’s because Mr. Larry chooses “to hang out with us instead of adults.”

The feeling is mutual and in full display after recreation time. The teen boys move in a mass of energy around Mr. Larry as he walks back to the hotel. Their forward pace unconsciously matches the older man’s slower steps. They circle him with skips and high fives. Mr. Larry smiles and feeds off the raw energy. There’s a pep in his step. He’s living his best life. Don’t remind Mr. Larry that he is 86, for when he’s with missionary kids, he is one of them and so much more.