Flawed film succeeds on the strength of its lead

Jillian Bell is having a moment, and we are here for it.

Bell has evolved from a scene-stealing character actress and now finds herself in the midst of a summer in which she has been able to do more with more screen time, first in “Sword of Trust,” and now with a proper lead role in “Brittany Runs a Marathon.”

The film has its flaws. That it succeeds overall only further establishes that Bell can carry a movie on her own.

Brittany Forgler (Bell) is a young New Yorker living a young New Yorker life, which is to say a fair amount of “hot mess” applies.

When she stops at the doctor, ostensibly to try and score Adderall, her doc tells her that she needs to control her weight.

Since a gym membership is out of her budget, Brittany starts running with an overachieving neighbor (Michaela Watkins). She doesn’t look like a marathoner at the start, but it’s a step in the right direction for her, and it leads to other important life changes.

We knew Bell was funny, but this performance displays more emotional depth than her previous work. In some ways, it reminded me of Jenny Slate’s similar turn in “Obvious Child.” There’s an aspect of, "Wow, where did that come from?"

There are elements of a coming-of-age story here, making the movie play like a bit of equal opportunity for the man-child comedies that Judd Apatow and colleagues have trafficked in for years.

For Brittany, it’s not so much about the physical transformation as it is taking steps into a healthier version of adulthood, one in which her self-image gets the makeover. In a nutshell, she learns how to love herself. (And, yes, there’s even a Lizzo appearance on the soundtrack.)

While writer-director Paul Downs Colaizzo gives Bell the chance to display a range of emotions, this can also be an issue as the tone glides along the comedy-drama spectrum. And there are some misfires in both lanes.

It’s uneven, and the ending is borderline hokey, but overall “Brittany Runs a Marathon” will leave you feeling good as hell.