We all start (and restart) somewhere. Brittany Runs a Marathon reminds us that running is usually about more than miles or weight loss.

There’s this one second in the new movie “Brittany Runs a Marathon” that I keep thinking about. It’s the day that Brittany, played by Jillian Bell, decides to go for a run for the first time.

After she changes into what she considers running-appropriate attire, she walks down the stairs of her Queens apartment building and reaches the front door.

The camera pauses on the brass doorknob, with Brittany’s hand resting on it. You don’t need to see her face to know she’s terrified.

It’s that feeling, right before you step out the door. I don’t remember it from the first time I went for a run, but from the many times I’ve started over since then—after injuries, illnesses, or inexplicable (inexcusable?) hiatuses. It’s a horrible combination of dread, fear, and vulnerability that stems from a lack of fitness, the knowledge that it’s going to feel impossible, and some embarrassment that you let yourself get so far off track.

And yet all of us as runners, at some point, still choose to face these significant personal insecurities—out in the world, where anybody can watch.

In the movie, which is based on the true story of writer Paul Down Colaizzo’s best friend Brittany O’Neill, Brittany is a 27-year-old who is lost. She parties a lot, she has a dead-end job at a movie theater, and has no self-esteem. She veils her lack of confidence in humor (which Bell does brilliantly). But when she visits a doctor in search of an Adderall prescription, she instead leaves with advice to lose 55 pounds to alleviate high blood pressure and other impending health complications from being overweight.

As the title indicates, Brittany ultimately does run a marathon—the New York City Marathon. But her journey there isn’t a fairytale and in the end, it’s not about running, really, either. It’s about using running as a means to improve your health, but also to improve your life.

I saw a screening of the film at the 92nd Street Y in New York, where Bell also did a Q&A after the movie, moderated (hilariously) by her friend Kate McKinnon, of “Saturday Night Live” fame. My nostalgia level was high. I started running consistently in my 20s when I lived in New York, in an apartment just two blocks away from where I sat that night. My first marathon was the New York City Marathon. I took two of my running buddies to the screening with me—one whom I met 15 years ago on the NYRR Team for Kids, when we trained for the marathon while raising money for youth-running programs.

“Brittany Runs a Marathon” is a transformation story. And yes, she does lose weight. But like any movie, what we take from it depends on our personal experiences.

Had I watched this movie a few years ago, I probably would have said, “It’s cute; worth seeing,” and left it at that. But my own struggle with running—and eventual return to it—in the past four years allowed me to come away with more. What I noticed above all is how running can serve as a stabilizing force in our lives and we don’t usually realize how much so until it’s gone.

Without giving away too many spoilers, it’s running that leads Brittany to a new support system and healthier friendships. She learns that regardless of how fast somebody is or how fit somebody looks, we’re all struggling with something in our lives. Eventually she chooses to stay in instead of hitting the clubs because she has an early morning run on her training schedule. And she learns to accept help from the people who offer it.

Brittany Runs a Marathon
PHOTO: Amazon Studios
Jillian Bell (left) stars in Brittany Runs a Marathon.

Not all of this comes in a neat Hollywood package—which is good, because nobody who has started running for the first time or trained for a marathon would buy it. What I enjoyed most about “Brittany Runs a Marathon” was its authenticity. During the Q&A, Bell explained that while preparing to shoot the movie, she also started running for the first time, eventually losing 40 pounds, but changing in other critical ways, too.

“I looked at the way I thought about myself or talked about myself. I would make jokes before I thought anybody else would and just sort of thought, ‘I’m not going to do that anymore,’” Bell said. “Women’s relationships—and men’s too—with their bodies are so layered and deep and it’s a relationship we’re with our whole lives.”

Bell also described how by running as a beginner, she better understood the script. When she went out for her first run, Bell’s sister filmed it so Bell would remember what it was like and how her posturing and breathing would evolve as she gained more experience and stamina. She clarified that she wasn’t required to run or lose weight to star in the film.

“There were parts [of the script] where I thought I don’t understand why she’s doing that there and I thought the physical journey would inform the emotional journey,” Bell said, “and it really did.”

How?

“I know that the first few runs I had when I was at home doing it on my own, they were tough and I was embarrassed and I felt very vulnerable,” Bell said. “When I read the script, I couldn’t believe how accurate it was to what I was experiencing.”

And that’s only part of what “Brittany Runs a Marathon” gets right. It’s in that vulnerability that we find the friendships, the ability to give and receive empathy, and a few important coping mechanisms for all the ups and downs along the way.

In a week I’ll be lining up for one of the only races I’ve trained for in several years, not to see if I can set a personal best (I won’t), but to celebrate my own return to running. I’ll probably pause at the front door before I head out to the starting line and feel that old, familiar trepidation, but I hope I’ll also think about what the movie reminded me: to recognize no matter what our ability, running can transform us and help carry us through this life if we let it.