“Write what you know,” aspiring novelists and screenwriters are told. And Alexi Pappas knows long distance running, training for long distance running, and the mono-maniacal focus it requires to make it to the Olympic Games.

So that’s what her film debut is about. She co-wrote, co-directed and co-stars in “Tracktown, ” a quirky, light and entertaining coming-of-age romance about a runner raised for the Olympics, but a little distracted by First Love, an important part of her childhood and adolescence that she’s missed.

Plum Marigold (Pappas) is a minor celebrity in a town that celebrates track and field like no other in North America. Eugene, Oregon is “Tracktown,” and everybody knows the oddball girl who has pursued her Olympic dream almost since birth.

Her dad (Andy Buckley) is a track coach, and yes he’s kept her focused and sure, he’s probably living vicariously through Plum as she tries to make the U.S. Olympic Team.

Her pals — her teammate Whitney (Rebecca Friday) and her own coach (Sasha Spencer) — are runners. Her life is running “90-100 miles a week,” adding supplements to every meal, sprinting in water tanks, sleeping in an oxygen tent and referring to Bartlett’s Familiar Quotations for each day’s motivational aphorism.

“In long-distance running, the only opponent you have to beat is yourself — Haruki Murakami.”

“If you keep dreaming, the dreams that you wish will come true — Cinderella.”

But girl-talk while training has her wondering if Whitney’s “sex before a meet” regimen isn’t something else that could give her an edge. And there’s this guy, “Baker Boy,” she almost flirts with when she buys each day’s load of carbs and sugars. He’s played by Chase Offerle of “Thumbucker.”

“Tracktown” has the odd interesting supporting character. Rachel Dratch is the absentee mom who wants to be more involved with her girl’s life. And as mom is barely recovered from some sort of breakdown and there’s a little hint of apples not falling far from trees, Plum isn’t having it.

“You think I’m crazy?” she asks Sawyer, the Baker Boy.

“I think you’re extreme.” 

Because the oddest of the oddballs here is our leading lady. Plum has a savant-like focus and awkwardness. A finely-tuned athletic machine, lean and lithe, she frets over her body like many a 21 year-old, questions if all this running will limit her future chances of having a baby.

“I look like a BOY!”

Even when she drops the largest of hints on Sawyer, we wonder just how naive she is. And Offerle gives Sawyer an offhanded sweetness with just enough hint of “What are HIS motives?” edge.

“Trackdown” goes down easy, and the character portraits are just interesting enough to hold our attention. But you can’t help but wonder if there wasn’t a more interesting movie that cut closer to home.

Pappas made it to the Olympics — by becoming a Greek, not US, citizen. She finished 17th in the 10,000 meters in Rio. She and co-director Jeremy Teicher have teamed on other projects (she co-write his “Tall as the Baobab Tree” and was in his “Speed Goggles”).

There’s something of “Rudy” in her personal story — triumphing against odds, self-promoting a not-exactly-epic athletic career and parlaying that into another career.

She’s got an affecting screen presence, in a Jenny Slate/Maya Rudolph sort of way. There could be a future for her in front of the camera.

But if nothing else, she’s made the most interesting behind-the-scenes portrait of track and training since “Personal Best,” a movie whose brevity is a serious flaw only in that we’re left wanting more details, more story and more of an ending that doesn’t feel like an ending at all, but an all-too-conventional “beginning.”

MPAA Rating: unrated, with sexual situations, nudity

Cast: Alexi Pappas, Chase Offerle, Rachel Dratch

Credits:Written and directed by Alexi Pappas and Jeremy Teicher. A Samuel Goldwyn/Orion release.

Running time: 1:28