What could possibly motivate someone with a full-time job and perhaps a family and a mortgage to devote an entire month of his or her life to something that will not reap one red cent?

Gene Kelly said it best in Singin’ in the Rain: “Gotta dance! … Broadway rhythm, it’s got me, everybody sing and dance!” Only those who have caught the musical theater “bug” can grasp the sacrifices performers are willing to make for the privilege of getting onstage to entertain. We can all be grateful, because without them one of Our Town’s most venerable community theaters might never have taken flight, much less have made it to the half-century point.

This year marks the 50th anniversary of Theatre in the Park, which each summer draws some 35,000 people to a grassy, bowl-shaped amphitheater in Shawnee Mission Park to watch an all-volunteer cast perform several great musicals. “There are just people who just want to sing,” said Tim Bair, a Kansas City native who performed all over the country before returning here in 2010 to become TIP’s producing artistic director. (He is also Manager of Fine and Performing Arts for Johnson County Parks and Recreation Department, the government agency that runs TIP.)

“Some have extraordinary talent, some have a little bit, but they still love doing it. … We have doctors, we have lawyers, we have people from all walks … who for some reason decided that it wasn’t something they wanted to pursue full-time as a career. But they still have a love for performing and for theater. … It’s their hobby.” And according to Tim, one shouldn’t underestimate the sense of community that these singer-dancers and crew members, some of whom perform on a near-professional level, enjoy: “the friendship, the camaraderie of being around a group of people who like the same thing you do, who find joy in it.” And, he added, with a laugh: “It’s a disease, really, isn’t it?”

Nearly 700 adults and children showed up in February this year’s TIP mass auditions, to perform in front of 25 directors, choreographers, music directors, and stage managers. This despite the fact that “none of the actors, none of the musicians, none of the crew receive any stipend of any kind,” Tim said. “So it really is a volunteer ‘donation’ of their time.”

This year’s TIP Outdoor lineup has included some of Broadway’s biggest family-oriented musicals: Annie (which Tim directed), Chitty Chitty Bang Bang, The Music Man, Matilda the Musical, and The Wizard of Oz. “We’re the most affordable theater in town,” Tim said. “I mean really, $8 for a whole night of musical theater? That’s a pretty good return.” (Kids 4-10 cost $6, and those 3 and under are admitted free.) Nearly all of this year’s shows make extensive use of young actors, several in feature roles.

This season’s opening outdoor production, Annie, featured gifted 10-year-old Holly Lichtenauer in the title role and nine other “orphans.” Some community theaters have used Annie as an opportunity to fill the stage with a sea of kids, but Tim wanted to stay closer to the authors’ original intent. “I wanted it to be a genuine as possible,” he said. Holly is an actor who “just ‘gets it,’ does it without effort,” he added. “She understands the humor, she understands the comedy. She’s really talented.”

Theatre in the Park is a rarity among performing-arts groups in our region: It functions under the auspices of a government agency, and receives nearly 40 percent of its funding from Johnson County itself. The company was founded in 1970 in Antioch Park, which it quickly outgrew: In 1980, Johnson County Parks & Recreation District decided to think big and make a space with room for growth. “Somebody had the good foresight to say, This is going to be huge,” Tim said. “So let’s make the choice now to put it in a section of the Park. I think that the ‘bowl’ itself was just the perfect hill for the stage setup, with that giant big lawn out in front of it.”

As for his own experience, Tim started getting the theater itch as a youth, at the Miller Marley School and at Wyandotte High School, where he was fascinated with “all the backstage equipment, the big light booms that you pull down, those big rheostat arms that you see in the ’30s movies.” Early on he performed in several Theatre in the Park productions, and was choreographer for TIP productions of Oklahoma! Seven Brides for Seven Brothers, and West Side Story.

After majoring in theater at Graceland University in Iowa he worked as a dancer and vocalist on cruise lines and eventually landed in New York City, where he was chosen for touring productions of 42nd Street and My One and Only. He served as artistic director of the Millbrook Playhouse in Pennsylvania and worked in several Western U.S. cities, including San Jose, where he was artistic director of that city’s American Music Theatre. In 2010 he returned to his native city to take up his current post.

This year, TIP hoped to draw as many as 40,000 to the Park, although weather always has its impact: At TIP the stage is uncovered, so unlike some outdoor venues in which perform32ers stay dry, at TIP any amount of rain provokes cancelation. TIP also operates a year-round indoor series at Johnson County Arts & Heritage Center: That season opens this Fall with Sweet Charity (October 11-27) and Disney’s Frozen, Jr. (December 6-15).

Three mainstage productions remain for the 50th anniversary summer: The Music Man runs through July 13th and is followed by Mathilda the Musical (July 19-27) and The Wizard of Oz (August 2-10). Gates open at 7 pm., and each show starts at 8:30 p.m. For tickets go to theatreinthepark.org.

To reach Paul Horsley, performing arts editor; send an email to paul@kcindependent.com or find him on Facebook (paul.horsley.501) or Twitter (@phorsleycritic).