Jillian Bell Improves Her Health, Personal Life in 'Brittany Runs a Marathon' Trailer

Utkarsh Ambudkar, Lil Rel Howery, Micah Stock and Alice Lee round out the cast of the Paul Downs Colaizzo-directed film.

In honor of Global Running Day on Wednesday, Amazon Studios has released the first trailer for Brittany Runs a Marathon.

The film follows New Yorker Brittany Forgler (Jillian Bell), who faces a roadblock when her doctor tells her that she needs to tame her wild lifestyle and get healthy. Initially at a loss, Brittany's seemingly perfect neighbor Catherine (Michaela Watkins) encourages her to lace up her Converse sneakers and go on a run around the block. After getting the hang of running and slowly building up her endurance, Brittany sets a goal to run in the New York City Marathon.

Utkarsh Ambudkar, Lil Rel Howery, Micah Stock and Alice Lee round out the cast of the Paul Downs Colaizzo-directed film.

The trailer opens by highlighting Brittany's unhealthy lifestyle. After she offers to buy a round of drinks for one side of a bar, she is later seen eating takeout and regularly drinking.

Brittany soon goes to a doctor's appointment in an attempt to get a prescription for Adderall. After the doctor denies her request, he tells her that she should lose 55 pounds. "That's the weight of a Siberian Husky," she responds. "You want me to pull a medium-sized working dog off of my body."

The main character continues to struggle with where she is at in her life as she fails to secure a new job and compares her life to others on social media.

In an attempt to get healthier, Brittany visits a gym but soon learns that she can't afford the high membership fees. "You do know that people can run outside," she tells the gym employee before a montage follows of her embarking on her first of many runs.

After Brittany decides to run in the New York City Marathon, she takes it upon herself to improve both her professional and personal lives. In addition to working out more regularly, she creates an online dating profile with the help of her new friend Jern (Ambudkar).

"My whole life the world told me I was lazy because the way I looked," Brittany later says in a voiceover as she continues to improve her physical and mental health.

The trailer concludes as Brittany struggles to run through Central Park. As she catches her breath, a group of young children effortlessly walk past her. "We're going backwards," she says.

Amazon acquired the worldwide rights to Brittany Runs a Marathon for $14 million following its premiere at the Sundance Film Festival. The film is set to open in theaters Aug. 23.

Watch the full trailer above.