Why Christopher Reeve's Kids Are Celebrating His Joyous Life in 'Unflinching' Doc That Doesn't Hide His Flaws (Exclusive)

The Superman actor's three kids open up about their father's life after the tragic accident that left him paralyzed — including how he found joy and a new sense of purpose despite never walking again

When Christopher Reeve’s children Matthew, Alexandra, and Will Reeve were little, their dad — who became a global sensation after he was cast in the 1978 film Superman — was the kind of guy who truly could do anything: fly planes, sail yachts, ski, ice skate, ride horses, play the piano.

He was also whip-smart and studied at Cornell and Juilliard. But as much as he seemed like a real-life hero, it was how he dealt with his life after his fall from a horse in 1995 that left him paralyzed from the neck down that left the biggest impact on his kids.

“Heroism is so much more than superficial strength and a glossy image," his son Will, 32, tells PEOPLE about his father's legacy. "It’s about integrity, showing up for your family, persevering through hard circumstances, and still having that joy for life. That was our dad.”

The actor's three children are thrilled to share a glimpse into their father's private life, both before and after the accident, in the new documentary Super/Man: The Christopher Reeve Story, playing in select theaters on Sept. 21 and again on Sept. 25 (which would have been Reeve’s 72nd birthday).

Related: Christopher Reeve's Son Reveals the Last Time He Saw His Father 'on His Feet' in New Super/Man Documentary

But as much as the film portrays the impressive way Reeve dealt with adversity and became an activist for the paralyzed community, the movie doesn’t gloss over Reeve’s life before the accident.

Indeed, he was famous and handsome, but he also had complexities, including a fractured relationship with his father, who was a strict professor he could never seem to please, and inner turmoil over being typecast as Superman.

He also walked out on his relationship with Matthew and Alexandra’s mom, British modeling agent Gae Exton, when the kids were young, leaving her heartbroken. The film helped the kids understand their father better.

“It’s a beautiful thing to be able to see the full picture of a person’s life,” says his daughter Alexandra Reeve Givens, 40, an activist who sits on the board at the Christopher & Dana Reeve Foundation.

She adds, “There were high highs and low lows but also two deep true loves and [three] kids that together blended into this beautiful family.”

Related: Christopher Reeve Wanted to Die After His Accident. He Said 7 Words from Wife Dana 'Saved My Life'

Reeve's first son Matthew, 44, a filmmaker whose footage from two previous documentaries he made about his father is used in the new film, also notes that they wanted to tell the full story of his dad's life.

“We intended to honor his story but not make it a sugarcoated puff piece,” he says, noting that it was also important to show how hard Reeve's life was after the accident, from learning how to breathe on his own without a respirator, to the cost and physical toll it took on the actor and his caregivers. including his devoted wife Dana who threw herself fully into taking care of her husband.

Will, who was nearly 3 at the time of his dad’s injury, says of Dana Reeve, “My mom was maybe the most special person to ever grace this earth. She had a unique combination of grace and beauty and compassion and grit and intelligence." All three children agree Dana was the glue that kept the family together after the accident.

The film's directors, Ian Bonhôte and Peter Ettedgui, say during the making of the movie they learned just how much Reeve changed, not just physically but also mentally, because of the injury.

“Christopher learned what was important after that,” says Bonhôte. “It wasn’t about making a successful film or more roles. It was his family, and focusing on his close bonds.”

Related: Christopher Reeve’s Son Will Confirms Cameo in Upcoming Superman, Says He Was ‘Nervous’ Shooting It

Alexandra says, “Our dad had a near-death experience, so he knew not to leave things unsaid. Because we suddenly weren’t doing physical activities, we had a lot more time to sit and have conversations hanging out in his office. That was a true gift.”

Will adds, “I watch Matthew and Alex be phenomenal parents ... with my mom and dad shining through them in the best way. You show up for the people you love and give them everything you have because you don’t know how long you have with them. That’s something I took from my childhood and will carry for the rest of my life.”

To read more about Christopher Reeve's extraordinary life, pick up the latest issue of PEOPLE, on newsstands Friday.

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