What is one small step off a curb for anyone else is one giant step for Gavin Stevens.

That explains why a 45-second video showing the 4-year-old, blind since birth, successfully navigating a sidewalk curb for the first time all by himself has gone viral, captivating the hearts of Internet viewers around the globe.

"We have been overwhelmed," said Gavin's father, Troy Stevens, who was there with his wife, Jennifer, to witness their son's milestone earlier this month.

Gavin, of Eastvale, Calif., was born with Leber's Congenital Amaurosis (LCA), an extremely rare genetic retina condition that left him blind. It has no cure. For the past five months, his parents said, Gavin has been training with a white cane to gain the ability to walk on his own.

He had previously only used the cane on flat surfaces, relying on his parents or another adult to help him along stairs and uneven surfaces. But on this day, after school, he decided to give the curb a try.

"I actually was walking with him holding his hand, and he pushed me away and told me, 'I can do it myself,'" Jennifer Stevens told ABCNews.com in an email. "So I stepped back and happened to have my phone in my pocket, and I shot the video."

Despite his bold statement, Gavin can be seen in the video wavering before telling himself, "I can do it," out loud and successfully navigating the step down to the street.

"For him, that was a huge deal because pretty much all the time now he wants to do it by himself," said his dad, Troy Stevens. "His confidence just blew through the roof. He tries to walk around everywhere by himself now."

For Gavin's parents, the attention the video has received - more than 400,000 views and growing - has left them "humbled" but mostly grateful for the attention it has drawn to those living with LCA.

Image credit: Courtesy Stevens Family

The Stevenses started a foundation three years ago, the Gavin R. Stevens Foundation, to raise money and awareness for the disease, which affects only 150 people in the U.S.

"We're just very thankful for all the support we're getting throughout the world and the nice things people are saying regarding Gavin," said Troy Stevens. "The awareness it's bringing is huge for us and for our foundation."

The attention has been just plain fun for Gavin, who has a big brother, 9-year-old, Landon.

"I don't think he understands how inspirational he's been for people, but he does know he's talked to reporters and he likes that," Troy Stevens said.