Nov. 6, 2007— -- Looking back at home movies of herself riding horses with her father, Christopher Reeve's daughter Alexandra Reeve remembers a cascade of magical moments.
"We grew up doing, I think, every physical activity known to man," said Alexandra, now 23 years old. "We sailed, we rode horses, and it was just a huge part of who he was as a person, and what we did as a family."
But Alexandra almost lost her beloved father on May 27, 1995, after he fell from his horse and became paralyzed from the shoulders down. Alexandra was 11.
Alexandra said the family had to figure out new ways of being together after her father's accident.
Matthew Reeve, Alexandra's brother and Christopher's son, was 15 years old on the day of the accident.
"He knew what he wanted to get done," Matthew said. "He had this focus, drive and determination."
Alexandra and Matthew grew up with a man the world saw as Superman. They came to realize just how appropriate the image was, not just in the days when it seemed he could do anything, but during the 10 years he lived in his wheelchair.
"He didn't want the role to define him," said Alexandra. "But he realized it did create a powerful icon to people, and the difference between a physical Superman, and then the strength that comes afterwards, is a powerful one, and he realized that if that sent a message of hope to people, then so be it."
It is a message they want to spread, and so, they agreed to a rare interview with "Nightline." Matthew, now 27, is a documentary filmmaker, and Alexandra, 23, is in her final year of law school. And while we have caught glimpses of them over the years, they have rarely spoken in public, and their British accents are a surprise.
"They're not — it's not fake," said Matthew, laughing. His sister added, "We were raised in England, and went to school over there, then grew up coming back and forth between England and America."
It was while at home in England with their mother, Gae Exton, that they first heard about the accident from their stepmother, Dana.
"[We] got a phone call from Dana very early in the morning," said Matthew. "Then we were on a plane later that day. [We] just didn't quite know what to expect."
They arrived to find their father was in dire condition, suspended between life and death, with no movement or sensation below his shoulders.
Five months after the accident, while still in rehab, Christopher Reeve sat down with my colleague Barbara Walters and talked about those first painful days, how he even thought of ending it all, until his family came into his hospital room.
"The minute they all came in, and I could see the love, and feel the love, and know that we're still a family, and that we're great," Reeve told Walters.
Alexandra remembers that moment. "I think anybody in that situation deals with doubts and with fears like that. You know, you're in this new universe, and just don't know what it's going to be, and your life is changed so fundamentally. But really, for Dad, that moment was just a moment, and then it was the instant realization that … he still had us around, so we needed him, and we wanted him to be there."
Five years after the accident, Matthew decided to document his father's journey — recording the victories, the painful setbacks and the humor.
"I was visiting Dad and Dana one week, home from college," Matthew recalled. "Dad pulled me aside and he's like, 'Hey, check this out.' And he moved his index finger on command. I was blown away. And I thought it an excellent starting point for a documentary."
It was truly remarkable. Doctors had long believed that someone with an injury like Reeve had suffered would never improve. Reeve proved them wrong. Despite the skeptics, he made further progress, regaining sensation throughout his body and moving his legs while doing therapy in a swimming pool.
"I think that that is one of the things that just kept Dad going every day, was waking up in the morning and thinking that physical therapy was his goal," Alexandra said.
Reeve's children say this mental discipline came from his career as an actor.
"He used to say that acting is a profession full of rejection," Alexandra said. "Particularly in the early years, and you have to have incredible motivation to keep going."
"His point of view was, he needed to have his body ready for the doctors when there was a treatment available, so that he could get back up on the horse, or, you know, fly again," said Matthew.
He would never walk, ride or fly his own plane again. But his two grown children say, because of him, and the foundation he and Dana created, others will.
Participants include Chase Ford, a 3-year-old who participated in one of the foundation's treadmill walking therapy programs — therapy Reeve himself used.
Chase, who fell off a sofa, sustained injuries similar to those of Reeve.
"It's a life sentence in a wheelchair, he was told," said Alexandra of Chase's condition. "Two years old at the time he was injured, he participated in a treadmill walking therapy, and now he's walking. Three years old, and walking."
Alexandra and Matthew now sit on the board of the Christopher and Dana Reeve Foundation, which has funded both research and quality of life grants for thousands of organizations over the years.
Some people criticized Reeve for saying that he would walk again. They said that this was just a form of denial. Alexandra doesn't agree.
"For him, it was absolutely a goal," she said. "And it was something to work for every day."
But as Matthew's documentary shows, every day wasn't easy.
"I think that's one of the most powerful things in the film, showing that it's not always easy, and that it is a struggle," said Alexandra.
Despite the struggle, Alexandra said, "our family dynamic didn't have to change."
"That was a very powerful thing, when Dana said to Dad, 'You're still you, and I love you,'" she said. "That's something that carried on for the full 10 years that he had after that."
As does the legacy their father left behind. A man who played a hero and then became one.