After a stroke, a 15-hour surgery, and 154 days of hospitalization, Derek Marshall set a goal: To walk with his Winslow Township High School graduating class.

"I knew it would be hard," he says. "But when I did it, I realized, 'I don't have to stop now.' "

That was in 2012. And he hasn't stopped since.

At 21, Marshall is midway through his freshman year at La Salle University, working as an intern at Independence Blue Cross, and maintaining an attitude of gratitude.

"Derek . . . is a fighter," Independence Blue Cross CEO Daniel J. Hilferty says via e-mail, adding, "I know Derek possesses the dedication and commitment to achieve incredible things."

Marshall has been embraced by Fred's Footsteps, a Philadelphia nonprofit founded in memory of Blue Cross president and CEO G. Fred DiBona Jr., that helps working families like his in financial distress due to serious illness.

"I know there are a lot of people who have had hardships like I have but who haven't the same opportunities," he says in a voice that's sonorous and clear after months of speech therapy.

"I want to help fill that gap for others. I want to serve my community and the world."

Marshall grew up in Sicklerville, Camden County, a bright, competitive fellow with a good sense of humor and a talent for music. He moved with his family to West Philadelphia in 2013.

That's where I meet the former high school multisport athlete, as well as his mother, Deloria, a customer service representative at Subaru of America in Cherry Hill; and older brother Eric, 22, a Community College of Philadelphia liberal arts major. Marshall's sister, Delisa, 25, is overseas with the N.J. National Guard.

"Derek has always been fiercely independent," says Deloria, adding that her 6-foot-4 youngest son was perfectly healthy until he developed a persistent headache in July 2011.

A mass of malformed blood vessels, called a cavernoma, had ruptured in his brain. When he awoke from surgery at the Hospital of the University of Pennsylvania, his left side was paralyzed, as was the right side of his face.

The college football career he'd dreamed of was gone. He was told he would no longer be able to play the bass or the cello.

Marshall was only 17. But he wasn't afraid of a challenge.

"Nothing is given to you," he says. "If you want something, you have to work hard."

Marshall underwent rehabilitation at Children's Hospital of Philadelphia and later at Children's Seashore House in Atlantic City. Progress was sometimes slow, but "whatever limitation they told him there would be, he went beyond it," Deloria says.

"I don't believe I have any limitations," says her son. "Physical fatigue really isn't that significant when you persevere."

His vision, hearing, and mobility are improving gradually, adds Marshall, who no longer uses a cane.

Besides at work and school, he speaks to support groups for pediatric stroke patients and helps raise money for Fred's Footsteps.

"Derek has become such an advocate," says Children's Hospital social worker Lois Robbins. "He's changed his life."

At La Salle, where he plans to major in business, Marshall sings in the gospel choir and is director of fund-raising for the university chapter of Enactus, a global organization that assists people in need.

That's the sort of thing Marshall would like to do professionally. But "getting through college is the next big thing," he says.

Based on the hurdles he has surmounted so far, I wouldn't be surprised if Marshall is able to accomplish that. And more.