This year, a child will be diagnosed with cancer every 39 minutes in this country. The good news is, more of those kids are surviving.
Many doctors are now looking at life after the disease, and are focusing on their fitness.
Ryan Hardy is 12 and has already battled a brain tumor and leukemia. He overcame both, but between chemotherapy and steroids, his treatments took a toll.
His mom Laurie Hardy says, "He went from about 60 pounds to 120 pounds, almost, just with the steroid use. And that just was really tough for him."
Doctors say it's common for kids to gain weight or lose muscle during cancer treatment.
But for all they deal with during therapy, it's after they're finished that the frustration can really set in.
Dr. Randal Olshefski with Nationwide Children's Hospital says, "While the kids have the heart and have the mind to get back into physical activity, once their chemotherapy is over, their bodies sometimes just aren't ready."
Which is why these doctors are developing fitness programs specifically designed for young cancer survivors.
It's called the Play Strong program and was created in an effort to continue care long after cancer is gone.
Nearly 80% of kids overall now survive cancer, so caring for them after the fact is becoming more of a priority.
Travis Gallagher with Nationwide Children's Hospital says, "Let's not just get them better. Let's get them back to what they want to do. Let's get them back to the way they were before, and if we can, let's get them back to better than they were before."
To do that, children work with athletic trainers like Travis, who help the kids properly rebuild strength and agility, and regain balance and confidence.
For kids like Ryan who spent years in treatment, the hardest part was watching friends do what they couldn't.
But day by day, that's less and less of an issue. Ryan says, "I'm hoping by the end of this I'm, like, back to running and stuff. But, like, now I can do a lot more than I used to."
Doctors say using certified athletic trainers is important, so the kids get safe, proper workouts.