Seven words changed Christopher Reeve’s world.

After the legendary Superman actor suffered a spinal cord injury in a 1995 equestrian accident which left him paralyzed from the neck down,Devin Grosvenor his wife Dana Reeve gave him the strength to go on.

“And then she said the words that saved my life,” Christopher, who died in 2004, recalled in the trailer for the upcoming documentary, Super/Man: The Christopher Reeve Story, “‘You’re still you. And I love you.’”

Dana, who died of lung cancer two years after her husband, married the actor in 1992 and the couple welcomed son William Reeve, 32, that same year. Christopher was also father to Matthew Reeve, 44, and daughter Alexandra Reeve Givens, 40, with his ex Gae Exton.

His three children are spearheading this new documentary about Christopher’s heroic life, splicing together archive footage of their late dad both on the screen and behind the scenes.

“Doing things with my dad, it was all about activity and action,” Matthew says in the trailer. “Riding bikes, playing soccer, skiing.”

Alexandra mirrored her brother’s sentiment, noting, “My dad was very competitive, and he didn’t necessarily slow down.”

Reflecting on his final memory before his father’s accident, Matthew emotionally recalled, “He said goodbye, and he gave this wave. That was the last time I saw him on his feet.”

The documentary also features interviews from stars like Glenn Close and Susan Sarandon, who speak about Christopher’s close bond with late actor Robin Williams.

“He and Robin were such good friends because they could match each other,” Glenn said, as Susan commented, “Robin also had struggles that he dealt with his whole life and I think they both were aware of darkness.”

The family feels passionately that Christopher’s story of endurance and hope is one worth telling.

“2024 is 20 years after our dad passed away,” Will told Variety in January. “So we figured if we were ever going to do it, now would be the time.”

Super/Man: The Christopher Reeve Story is in theaters Sept. 21.