This 13-year-old runner is among the youngest tackling the United Airlines New York City Half Marathon on Sunday — and she’s got one of the biggest hearts.

Ciera Sesock, an eighth grader from Visalia, Calif., has spent almost four months raising thousands of dollars and pounding out hundreds of miles with the American Cancer Society’s DetermiNation team to honor her aunt, who died from lung cancer two years ago. And she’s logged those miles despite being diagnosed with Allergic Bronchopulmonary Aspergillosis (ABPA)  – a fungal lung infection that makes it harder for her to breathe while she’s on the run.

“It usually causes me to breathe hard, have chest pain, coughing or have a really bad wheeze,” Ciera told Moneyish. “My friends kind of think I’m crazy, because I have a lung condition and I’m running a half marathon, but hey, I think it’s a good idea.” (And yes, she has the blessing of her pulmonary specialist, who supports anything that keeps Ciera active, because the goal is to enable her to do the activities that she desires.)

ABPA impacts 4.8 million people worldwide, according to the CDC, but because aspergillosis is not a reportable infection in the United States, the exact number of cases is difficult to determine. Ciera was diagnosed at the Children’s Hospital of Philadelphia last summer, and she uses a nebulizer and inhalers every day to clear her airways so that she can still run and play soccer. She also carries a rescue inhaler as needed during the day; the doctors and her mother are teaching her to be her own advocate in pain.

“I’ll take precautions and use my inhaler beforehand or during a run, and sometimes if it gets worse, I’ll just have to stop for a little bit to let it get better,” Ciera said. “But you just have to keep on going.”

Ciera Sesock, 13, has been training for the NYC Half Marathon for charity despite a lung condition. (Charaighn Sesock)

Ciera has run 5Ks and 10Ks (3.1 and 6.2 miles, respectively) but this will be her first half marathon – and at 13.1 miles, the longest distance she’s ever run. She’s joining a field of more than 22,500 runners hoofing it from Brooklyn’s Grand Army Plaza, across the Manhattan Bridge and through Times Square, before finishing in Central Park.

Also read: 7 life lessons from New York City Marathon winner Shalane Flanagan

“New York is one of my favorite cities, and I just thought, ‘Go big, or go home,’” said Ciera. “And this was a great way to be a role model for my peers, and to honor other cancer patients that were like my aunt.”

Her mother Charaighn Sesock, who works at the American Cancer Society, will be running by her side. They’ve been training together, which has entailed doing two to four miles on weekday afternoons two or three times a week, followed by long, slow runs of between six and 12 miles on Saturday mornings.

Ciera Sesock, 13, has been training for the NYC Half Marathon for charity despite a lung condition. (Charaighn Sesock)

“I’m so proud of where she is at, especially with all of the frustrations that come with this diagnosis,” Sesock told Moneyish. “And it’s been really fun getting to know her on a different level other than the everyday mom/taxi driver. We’ll talk about what’s been going on in school, and sometimes we’ll play music on my cell and argue over what song to listen to. I like slow songs like ‘Let It Go’ from ‘Frozen,’ but Ciera wants to listen to hip hop and rap.”

Ciera countered, “It needs to have a good beat to run to.”

Ciera Sesock, 13, has been training for the NYC Half Marathon for charity despite a lung condition. (Charaighn Sesock)

She and her mother are hoping to finish in under two and a half hours, although the end goal is just to finish strong. “She has to really listen to her body and make sure that she is taking care of her breathing needs,” said Sesock, a seasoned runner herself whose fastest half marathon finishing time is one hour, 35 minutes (pretty speedy considering the median time for women running a half in 2015 was 2 hours, 22 minutes and 21 seconds.)

Also read: Participants in this sport may be the most charitable athletes in the nation

On the fundraising front, Ciera had the brilliant idea to record a video detailing her training and describing her lung condition, while also telling potential donors about how the organization will use their dollars to help cancer patients and their families. “It was a good way to tell friends and family about what’s going on and why I’m doing this,” she said. “And I would also say, ‘If you give a $10 donation, I’ll put the name of a loved one on my shirt,’ and now I’m running with about 25 names in total, in memory or in honor of people who had cancer.”

She’s raised more than $2,300 and counting.

Ciera Sesock, 13, has been training for the NYC Half Marathon for charity despite a lung condition. (Charaighn Sesock)

Pitching her cause to potential donors and working toward a long-term goal has instilled important skills that Ciera can apply toward becoming an architect or an engineer, her two dream careers at the moment. “I’ve learned that I just have to time-manage. You have to make sure that you leave space for each thing that is a priority to you, and if you manage time well, you won’t miss out on anything,” said Ciera.

And she’s also learned the invaluable lesson of helping others. “I just love that she’s so inspired, that even despite her health problems, she’s out there fundraising. I’m so proud that at such a young age, she is already thinking about how to give back to the community,” said Sesock. “We’ve had a lot of ups and downs in this whole process with her training and her health, but she hasn’t given  up. And I know I wasn’t that determined when I was 13.”

Ciera chimed in, “I just want to do this so that I can inspire people and make a difference.”

Click here to support Ciera’s run.

Ciera Sesock, 13, has been training for the NYC Half Marathon for charity despite a lung condition. (Charaighn Sesock)