"Here I am, a 300 pound powerlifter hanging on to a 25 pound little girl for support," said David "The Beast" Douglas, a 29-year-old ex-Marine.
When ex-Marine powerlifter David "The Beast" Douglas was asked to meet a young girl with a rare genetic disorder at a charity event three years ago, the meeting sparked an unlikely friendship.
Now the 300-pound man tells InsideEdition.com that 12-year-old Lindsay Ratcliffe continues to change his life more than he could ever have imagined.
Read: Deputies Surprise 7-Year-Old Boy Suffering from Terminal Illness with 'Thriller' Dance
Being adopted into an Italian family shortly after birth, Douglas said he was taught to see past what someone looks like, and to "only see the personality in people."
Perhaps this is what solidified his bond with Lindsay. When she was 4, she was diagnosed with progeria, a disease that ages people eight to ten times faster than normal. But "you would never know she was fighting something so hard," Douglas said.
Douglas told InsideEdition.com that he had been powerlifting for years when a representative from Relentless approached him in 2013 and invited him to join its cause. The biannual powerlifting competition aims to raise money, awareness and support for children diagnosed with life-threatening illnesses, according to its website.
Douglas said he was at a low point in his life and, when he was asked to give back in the form of a weightlifting competition, he couldn't turn it down.
When he arrived at the Relentless Detroit competition that year, he knew there was a little girl already looking forward to meeting him but he was not nearly prepared for her introduction.
He told IE.com that he was sitting toward the back of the stage when all of a sudden, a girl began running toward him.
Read: 78-Year-Old Granny Who Can Lift 228 Pounds Reveals How She Discovered Her Hidden Talent
"She gave me a little bracelet to wear that she made for me. She went on to tell me that she watched all my videos on YouTube, and she was a fan," Douglas told IE.com. "That humbled me. Someone in her position, going through so much stuff to have time to look at my stuff on YouTube."
The 29-year-old powerlifter said that he was fighting back tears when it was his turn to hit the stage.
A now viral image, which shows him hand-in-hand with Lindsay, was taken at the following Relentless competition, held in Minnesota.
Following that competition, Douglas and Lindsay had headed to the Mall of America, where she suddenly remembered that Douglas had a fear of rollercoasters.
"I was trying to convince her, 'Is there anything else you wanted to do?'" Douglas said. "She took me by the hand and dragged me to the rollercoaster."
Sensing that he was nervous, Lindsay reassured him: "It's okay David. You can hold on to me."
"Here I am, a 300-pound powerlifter hanging on to a 25 pound little girl for support," Douglas joked. "Another humbling moment to say the least."
Douglas said he later added the words "strong" and "stronger" to the picture - with the latter indicating his young friend.
Read: Sister Surprises Her Widowed Twin With Home Makeover
Since then, Douglas and Lindsay have remained friends. Lindsay even flew out to California when she heard Douglas was undergoing surgery for a torn bicep.
"Right before I was going back into surgery, [the doctor] opened the curtain, and Lindsay and her family was there," Douglas told IE.com. "All the stuff they're dealing with, but to pick up, and get on a plane to support me ... They changed my life in so many ways, they don't even know it."
Douglas said that as his family and the Ratcliffe family waited for him to get out of surgery at his house, Lindsay and his 10-year-old daughter Angi also became fast friends.
"They went to their rooms and started doing girl stuff," Douglas laughed.
Read: Justice Served For Juliette?
Douglas has since returned the favor by surprising Lindsay in her hometown of Flat Rock, Michigan. Her parents told Douglas that she leads a walk every year to raise money for progeria research.
Even though Douglas had originally told her that he wouldn't be able to make it, he ended up flying across the country to surprise her for the big day.
"She ran into my arms -- one of the best moments of my life," Douglas said. "I will forever remember that moment, and that feeling of seeing her run to me and smile."
Douglas told IE.com that they continue to keep in touch. He said he talks to her family on Facebook at least once a week, and tries to chat with her via Facetime "every chance I get."
In several posts on Facebook, Douglas said he considers Lindsay his "little sister."
Douglas said that he also invests time in other children through Relentless Detroit, which he said has raised over $1 million since its start in 2012.
He also recently helped raise money for sisters Kaylee and Serenity, who were both diagnosed with CDG type 1a, making it nearly impossible for them to walk. Relentless fundraised money to get the sisters the intensive physical therapy they needed.
Relentless Detroit, where Douglas first met Lindsay, began as an offspring of Relentless Minnesota. The Detroit chapter was founded in the name of Austin Valentine, who was diagnosed with cancer when he was 9. He recently passed away.
Read: Fairy Godmother Gives Comfort To Grieving Mom Carrying Her Daughter's Ashes in Teddy Bear
Douglas told IE.com that in the end, it's all about the kids.
"They don't care how strong you are," Douglas said, "It's about making the kids feel like superstars."
Watch: Man with Muscular Dystrophy Plans to Travel Through Europe on Friends' Backs
