Determined blind boy, 4 year old Gavin Stevens, takes his first step off of a curb...

It was a small step but a huge feat for 4-year-old Gavin Stevens, who is blind.

As seen in a YouTube video, Gavin, of Eastvale, Calif., conquers the curb, using a cane and stepping off the sidewalk all by himself for his first time.

Gavin broke ritual that day: Normally after preschool, his mother holds his hand and guides him down the curb.

“No, I’ll do it,” he suddenly told his mom.

Mom Jennifer Stevens, 37, pulled out her phone to capture the anticipated moment on video. Since Gavin can’t see pictures, his mom keeps his memories in videos, which he can hear.

The video shows Gavin timidly walking to the curb with his little white cane, drumming up his courage by repeating, “I can do it.”

“You can do it, baby. Go ahead,” encourages his mom.

Inching his way to the curb, tapping his cane, Gavin steps down onto the pavement.

“Good job!” his mom cheers.

When asked if he was scared to take his step, Gavin, a normally chatty boy, told TODAY Moms, “Yeah.”

Months of hard work with a mobility therapist preceded Gavin’s milestone. He attends a special-needs preschool as well as the Blind Children’s Learning Center in Santa Ana, Calif., once a week, but will go to a regular kindergarten.

“He’s so determined,” Stevens said. “He doesn’t know he’s blind. I don’t think he understands he is different. We treat him like we do our oldest son. We just try to make sure he’s safe.”

Worrying about kids’ safety comes with the territory of being a parent — but that’s amplified with a child who literally can’t watch out for danger.

The issue of Gavin’s safety began even before he was born. A miscarriage scare forced Stevens on bed rest for much of her pregnancy. At birth, Gavin seemed happy and healthy, and he somehow passed all his pediatric eye exams, but Stevens’ intuition told her otherwise. An eye specialist later confirmed that Gavin was blind.

“That was the most devastating day of our life,” Stevens recalled.

In fact, Gavin was born blind. He has Leber's congenital amaurosis, a rare genetic disease (1 in 50,000) of the retina, the part of the back of the eye allowing us to see, retina specialists at Children’s Hospital Los Angeles determined.

“When we got the diagnosis, we started to heal,” Stevens said.

Healing involved starting the Gavin R. Stevens Foundation to learn more about LCA and seek a therapy for Gavin and kids like him. His mutation was unknown until geneticists in Oregon decoded it and discovered a new gene (the NMNAT 1 gene) linked to LCA.

Gavin grew up hitting milestones on his own terms. Always timid, he never crawled and walked late. For months, he wanted nothing to do with his little cane. Stevens, surprised the video went viral, had hoped the video would help families in similar situations.

“I thought it would be inspiring to other parents of children just starting to use a cane,” she said.

Gavin is starting to show special talents in things he can hear. Music brought him to life as a baby, and he now sings, plays various instruments and takes lessons at the Academy of Music for the Blind in Monrovia, Calif. Gavin remembers things he hears, names and song lyrics, especially well. (His favorite artist? “I like Pitbull,” he said.)

In addition to taking his step off the curb, Gavin experienced many other firsts this past year: He rode his first tricycle, played in his first soccer match, and recognized his first Braille letter, “G.”

His mom says that, at home, Gavin often insists, “No, I’ll do it.”

“Just in the last year, he came into his own personality,” said Stevens.

“I think he’s becoming more self-reliant. For me to capture that point in time in his life, it was a huge step not just for stepping independently but relevant to Gavin.”