9-year-old boy prepares to climb Mount Aconcagua in Argentina

YORBA LINDA, Calif.

Tyler Armstrong is like any other 9-year-old boy, but at his young age, he's already broken a number of records. In 2012, Tyler became the second youngest person to conquer Mount Kilimanjaro. What's even more impressive is at the age of 7, he became the youngest person to climb Mount Whitney in a day.

The fourth grader is now climbing with a mission: He's raising money and awareness for duchenne, which is a form of muscular dystrophy.

"They can't walk, and that's like the opposite of me," Tyler said. "I want them to climb with me when we find a cure."

Despite his previous achievements, Mount Aconcagua will be Tyler's toughest challenge. At 22,000 feet, it is an excruciating climb at below zero temperatures.

"It takes lots and lots of training," said Tyler. "I had to do ice-climbing training, so if I fall I can stop myself and not slide down the mountain. We're really working on my abs a lot. All the weight from my backpack and all the stuff that I'm carrying goes where your abs are."

Tyler's father and team member, Kevin Armstrong, says he would never put his son in imminent danger and remains confident that his son is ready. Each journey, he says, has been his son's idea.

Tyler and his father leave for Argentina on Dec. 7. Argentina's age restriction to climb Mount Aconcagua is 14, so the Armstrong family plans to get the local courts to approve a special hiking permit for the 9-year-old.

After Mount Aconcagua, there's one summit left on Tyler's agenda and that's Mount McKinley in Alaska.

ABC News contributed to this report.

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