he's a long snapper and a linebacker at edson high school alexandria, virginia. but a year and a half ago his life took an unpected turn. forcing him to tackle something much more riseous, cancer. >> i was pretty scared, but i was just wondering if i could get back to playing sports or if i was going to get back to being able to walk even. >> reporter: sebastian was diagnosed wh osteosarcoma, a rare bone cancer. he had to have his foot amputated. now he's walking, running, even swimming with help from a prosthetic. >> i built the device. i make sure it works. but he's the one that takes that to the next level. >> reporter: it's a remarkable marriage of science and strength. coming up tonight at news 4 at 5, we'll tak you inside the northern virginia lab that made t possible and show you h they're helping change lives around the world. that's tonight at 5. >>> just a reminder for you, chec out the annual nbc 4 telemundo 44 health and fitne expo at the washington convention center. there will be health screenings, experts to answer questions and we'll be there as w