“Usually whenever people are done with chemo, they’re just done with cancer,” 11-year-old Sadie Keller told CBS DFW. “They don’t want to talk about it anymore.”

A cancer encounter is something the North Texas girl knows firsthand: on February 25, 2015, when she was 7 years old, Sadie was diagnosed with Acute Lymphoblastic Leukemia.

But after surviving her own long battle with the disease, Sadie isn’t through—she’s still fighting for children struggling with cancer.

“I wanted to take my treatment and turn it into something that would help other kids,” Sadie said.

Screenshot via YouTube/CBSDFW

Even while she was having her two-and-a-half year challenge with leukemia, Sadie was reaching out to help other cancer patients.

Through her YouTube channel, Sadie, with an upbeat spirit, talked frankly about her cancer treatments and directly reassured children with cancer.

“There’s nothing that you do, that you ate, breathe, that would make you get leukemia. So, it just happens,” she said in one video.

For the past three years around Christmas time, Sadie’s organization Sadie’s Sleigh has collected toys for young cancer patients. Their most recent drive collected over 10,000.

Today, the girl is cancer-free, but keeps up the cause. She has started painting, and auctions off her artwork.

The money goes to programs like buying “parent packs,” gift cards for essential items given to parents of cancer patients, and “milestone gifts” given to patients at different stages of their treatment.

One of her paintings is a self-portrait, based on a photo of Sadie sleeping while undergoing chemotherapy—a reminder of how far she’s progressed.

“It makes me feel like I’m strong when I look at this painting,” Sadie said.

Screenshot via YouTube/CBSDFW

Sadie has also taken her cause to Washington. She has spoken in front of Congress on behalf of her fellow patients, trying to get increased funding for childhood cancer research.

“I was so upset [when I heard that], because people think childhood cancer is rare, when it is not,” she said.

Thanks in part to Sadie’s lobbying, Congress recently passed the STAR act, a comprehensive piece of cancer legislation. The girl was in the Oval Office as it was signed into law.

Screenshot via YouTube/CBSDFW

After surviving her own ordeal with cancer, Sadie knows firsthand how frightening and uncertain things can be, and the impact these small acts of kindness and hope can have on someone’s life.

“I was just so scared and nervous with all the rest of my family and I didn’t know what to expect at all,” Sadie said.

But now, Sadie has found her calling helping others, and is getting incredible results.

“[People] are just saying, ‘What you’re doing is making a difference,’” Sadie said.