High schoolers RJ Duarte and Owen Johnson run the Colorado company Green Worx Landscaping in the fourth episode of Small Business, the Moneyish original series about kids and teens who run their own businesses.

Lots of kids mow lawns. But RJ Duarte turned lawn mowing into a lucrative business.

A 17-year-old high school senior in Golden, Colo., Duarte started mowing lawns alongside his brother when he was 6 or 7. Now he juggles school, college visits and the demands of his company, Green Worx Landscaping, which offers lawn care, cleanups, snow removal and more in Colorado and is on track, Duarte says, to pull in a little over $100,000 this year.

“I found something that I enjoyed doing,” he said. “It might sound weird, but mowing lawns when you’re little is kind of fun.”

During middle school, Duarte realized he needed help with a growing roster of clients, and teamed up with his classmate Owen Johnson.

The pair realized they worked well together when they both had jobs in the school cafeteria. At Green Worx, they lead crews of their fellow high schoolers, who they start at $10 an hour, slightly above Colorado’s minimum wage. The company’s biggest commercial client this year is a waterpark and golf course; they’ve planted thousands of flowers at the property, which they maintain.

Scheduling is just one of the challenges Duarte and Johnson face running their business. In the summer, they start work in the very early morning and are out until dark. During the school year, they can wake up as early as 2:30 a.m. to get in as much work as possible before the school day begins.

Duarte says he’s had to assure teachers that he’s doing “completely adult stuff” when they catch him on his phone scheduling a job or touching base with a client.

“The cliché in school is you pull out your phone and you’re not doing something,” he says.

The teens have been able to scale up the company year after year with help from parents, a mentor in the local business community, and others in their network. In 2015, Duarte won a $1000 prize for young entrepreneurs through Young Americans Bank, a one of a kind bank designed for kids and teens that happens to be located in nearby Denver.

Duarte’s mom, Tamara, says she couldn’t be more proud that her son has been able to build a successful business while thriving in school.

“This kid has the drive, it’s like nothing I’ve ever seen in my life,” she said. “Once he puts his mind on something, he’s locked on.”