BOSTON -- Joseph Miller, 5, has dreams of being a rock star, and he's already hard at work on his first album.

But at 18 months old, when Joe still hadn't learned to walk, his parents, Eric and Dena Miller, became concerned. They took him to the Muscular Dystrophy Association Clinic at Children's Hospital, where they received a stunning diagnosis.

VIDEO: Child Battles Spinal Muscular Atrophy

"SMA is spinal muscular atrophy. It's a degenerative neuromuscular disease. His muscles are OK, and his nerves are OK, but the protein that allows them to talk effectively aren't there. So only some of his muscles get the signal. So he can still move his legs and his arms and things like that, but they're just not strong enough to sustain walking," Dena Miller said.

"When we got the diagnosis, it was just boom. It really was. My mind went blank," Eric Miller said.

That day, the Millers' close relationship with MDA began.

"They were always there to support us -- either just to talk, to vent, to talk about equipment needs," Eric Miller said.

"Just having a network of support and people that you can call, because there's not always a solution. There really isn't always a solution, but there's always a way to get through it with grace and dignity," Dena Miller said.

Today, Joe is MDA's Goodwill Ambassador for Merrimack Valley -- helping to raise money and awareness for the organization that has played such a large role in his full life.

"We can still do pretty much what we want to do. He can still do all the activities. We just have to figure out a way to do it," Eric Miller said.

They do it with MDA resources such as Quest magazine, where Eric Miller learned how to build a chair so Joe can go to the beach.

"They made some beach chairs at the beach that we use, and they can float on water," Joe said.

The Millers' hopes for Joe are just like other parents -- that he live a long and happy life.

"I still have dreams for my son. I want him to lead an independent and normal a life as possible. I want him to be dating at 16. I want him to meet girls. I want him to go to the prom. I want him to do all those things," Eric Miller said.

"I don't need him to walk. But you make damn sure that he doesn't die before I do. That's what I want," Dena Miller said.