Born with Lymphatic Malformation, a mass of fluid-filled cysts surround her mouth and jaw, Hubbard was about five years old before she knew she was different.
"Once she was in school, around other kids and reacting to the way they looked at her, she would look at me kind of puzzled," recalls her mother, Leanne, 44, of Moorestown, N.J.
But Kennedy didn't let those differences faze her.
"When I look in the mirror, I just see myself," says Kennedy, a setter on her school's volleyball team. "It is what it is."
Two years ago, when she was a freshman at Moorestown (N.J.) High school, she and her family launched Kennedy's Cause, which has raised more than $34,000 by selling bracelets, t-shirts and car magnets stamped with her personal motto – "Shine."
The money goes to fund research for better treatments and possible cures for her disease and to help other sick children and their struggling families, no matter what their disease or disability.
"She's dedicated herself to making this journey better for the next people," says Dr. Cameron Trenor, clinical research director of the Vascular Anomalies Center at Boston Children's Hospital.
"It's priceless, the perspective she gives on how kids can embrace their differences," he says, "and handle what are some very serious medical problems."
Kennedy's foundation helped buy an expensive medical bed for a girl in Hawaii with CLOVES Syndrome and gas money to a family in Ohio who drove two hours a day for six months to be with their hospitalized baby boy.
"From being in the hospital so many times, I've known so many families in need, kids littler than me who have similar medical issues," says Kennedy. "I want to give them hope."
Kennedy goes out of her way to befriend and mentor other children with Lymphatic Malformation.
Courtesy Caryn Shaffer
This past summer, that included cutting out of volleyball practice to travel to the New Jersey shore to meet with the vacationing Shaffer family from Culpeper, Va., whose 2-year-old son, Cole, has an almost identical lymphatic mass in his face.
"I was scared of the day Cole says to me, 'Why are they staring at me?' " says Cole's Mom, Caryn, 32. "But one response Kennedy told me that stuck in my head like a mantra is, 'Curiosity is OK; cruelty is not.' "
Kennedy's help was invaluable, she says.
"The hope Kennedy's given me you can't put a price on," she says. "I can now look down the road and see a bright future for my boy."
Know a hero? Send suggestions to email@example.com. For more inspiring stories, read the latest issue of PEOPLE magazine