EXCLUSIVE: Meet the Real 'Miracles From Heaven' Family

The Beam family chatted with ET about the film and how they really feel about Jennifer Garner bringing their story to the big screen.

The Beam family, whose story inspired the movie Miracles From Heaven, chatted with ET about the film and how they really feel about Jennifer Garner bringing their story to the big screen.

In the faith-based movie, Garner stars as Christy Beam, a mom who becomes a ferocious advocate for her 10-year-old daughter Anna (Kylie Rogers) when she is diagnosed with a rare, incurable disease. Their lives are forever changed when an extraordinary medical miracle unfolds, leaving specialists baffled and a community inspired.

"I was definitely inspired by who Christy is as a mom," Garner told ET.

WATCH: Jennifer Garner Finds Faith in First Movie Since Ben Affleck Split

Garner was always the first choice to play Christy in the movie, and ET found out why.

"We met for the very first time and she had my book," Christy told ET. "She had read Miracles From Heaven from cover to cover, and she'd underlined and highlighted and dog-eared."

The 13-year-old on which the story is based, Annabel Beam, now has no symptoms and she was just as pleased with Garner.

"She's really sweet," Annabel told ET.

WATCH: 'Heaven Is For Real' Boy Details Near-Death Experience

In 2011, Annabel fell 30 feet into a hollow tree while playing with her sister. The fall knocked her unconscious and Annabel says she went to heaven and met Jesus. The accident seemingly cured her from a rare and potentially fatal digestive disorder.

"Heaven was very bright and it was very peaceful," Annabel told ET of her experience. "There was no pain, and that's why I wanted to stay. And I sat on Jesus' lap and I asked Him if I could stay. He said, 'No, Annabel, I have plans for you on Earth that you cannot complete in heaven, but whenever the firefighters get you out, there will be nothing wrong with you.'"

Annabel described Jesus as having brown hair, a beard and wearing a purple sash.

WATCH: Jennifer Garner Says Filming 'Miracles From Heaven' Reminded Her of What 'Really Matters'

Miracles From Heaven opens in theaters March 18, but ET was with the Beam family earlier this week as they prepared for the red carpet premiere in Los Angeles on Wednesday.

Watch the video below to see the Beam family dish on their favorite parts about being at a Hollywood red carpet event.