Tyler Armstrong is only 11, but he’s scaled some of the world’s fiercest mountains. Next: Everest

Climbing Mount Everest is no easy feat for anybody, but 11-year-old Tyler Armstrong thinks he has what it takes.

The Yorba Linda resident has climbed three of the world’s seven highest summits, Kilimanjaro in Tanzania, Elbrus in Russia and Aconcagua in Argentina, where he broke a world record for being the youngest person to climb it at age 9.

Now he’s gearing up to scale the highest mountain in the world in May and perhaps set another record because of his age.

“It all started when I was 6 years old during winter break and watching a nature documentary on the Great Divide, and after that I told my parents I wanted to start hiking,” Tyler said.

But how did that simple start lead to scaling some of the world’s highest peaks?

“The next thing after hiking is climbing,” the boy said.

And that idea led to a mention of tackling California’s Mt. Whitney, the highest summit in the contiguous United States.

His parents, Kevin and Priscilla Armstrong, neither of whom are mountain climbers, thought this was a phase and that it would blow over, so they indulged their son with that in mind.

“We did think it was a little silly and wouldn’t stick,” Priscilla said. “We live near a lake, and we said if you run around the lake each day, we would take you climbing Mt. Whitney.”

The son followed through — so the parents did too.

“We figured after he climbed Mt. Whitney, he would be done and we would move onto something else,” the mother said.

It didn’t happen.

Now, Priscilla said, she and her husband don’t want to squash Tyler’s dreams. Kevin has learned about the sport, particularly the safety aspects, and joins his son on his treks. On the biggest mountains, they also have an experienced guide.

Tyler, a Boy Scout, said he has a strict training regimen that helps him prepare for his climbs.

Every morning before school, he walks on a treadmill while carrying a 25-pound backpack. After school, he jogs around the mile-long lake near his house.

He also works with personal trainers and mountaineers who have climbed Everest, and climbs local mountains once or twice a month.

“There’s no real secret to it,” Tyler said of climbing. “You just have to really put your mind to it. I think it’s much harder to go do something if you don’t train for it.”

He plans to climb the north side of Everest, in China.

Kevin said China usually grants permits for Everest only for climbers between ages 18 and 66, but officials indicated that they will make an exception for Tyler because of his background.

The family should find out by March or April if the mountain will be open and if Tyler will be issued a permit. The mountain was closed this year because of an earthquake and avalanche in Nepal.

This year, Tyler has an added incentive to conquer Everest, to raise funds to conquer Duchenne, a form of muscular dystrophy that also affects breathing and the heart. Patients typically don’t live beyond their 40s or 50s, according to the Muscular Dystrophy Assn.

“After I did my first climb, Mount Whitney, four years ago, I went to a barbecue and asked my parents why a boy couldn’t walk,” Tyler said. “They told me about Duchenne and asked if I wanted to help out. I said yes, and that’s where it all started.”

Since launching a fundraising campaign three months ago on CrowdRise.com, Tyler has raised more than $9,000 for Cure Duchenne, a Newport Beach-based organization that supports awareness and research. His goal is to raise $1 million for Cure Duchenne through support for his climbing.

“He’s got a huge heart, and the fact that he’s willing to do this for kids with Duchenne is huge,” Kevin said of his son. “On the mountain, he’s like an adult. He teaches me things. It’s impressive to watch my son, even at such a young age, be so good at something. Some of the best times I’ve ever had in life have been with Tyler on the mountains.”

Tyler said he loves the experience of climbing and sense of accomplishment.

“It’s not so much that I want to get the record,” he said. “That’s something that comes with it. When you get to the top, that’s what I’m most proud of usually, because all that hard work finally paid off.”

—Debbie Zucco contributed to this report.