Joe and Ali Olson spend their days traveling around the world with their one-year-old daughter, Annabelle.

Each in their early 30s, the couple were able to quit their jobs as public school teachers in August 2015 and retire after just eight years in the workforce.

How do you retire early as a public school teacher? The key: minimizing cost of living and finding a good side hustle.

The Olsons met in 2004 when they were both college students, and got married during winter break of their senior year. Straight out of college they moved to Las Vegas, where Joe had accepted a teaching position with Teach For America. Ali started as a substitute teacher and eventually joined TFA as well, teaching English at a local high school.

“Luckily, Las Vegas has a really low cost of living — but it also has a low teacher pay,” Ali told the Mad Fientist on an episode of his “Financial Independence Podcast.”

So they took on any extra jobs they could — teaching summer school, running clubs, after-school tutoring — to bulk up their salaries. “It’s a big difference percentage-wise because if you’re making $35,000, and you teach summer school for $3,500, it’s like, ‘Wow, there’s a 10% boost in my salary,'” Joe explained.

Some years, they were able to boost their income by as much as 50% through these supplemental positions.

Eventually, the couple realized they wanted to achieve financial independence and have the freedom to pursue whatever dreams they wanted, whenever they wanted. They continued to live frugally, saving around 75% of their teaching incomes, and in 2008, they bought their first rental property in Vegas.

In the following couple of years, the couple scooped up 14 more rentals. Though they lost money on these during the financial crisis, the market eventually turned and their properties starting bringing in steady profits, eventually pushing their net worth over $1 million.

Now, they’re completely financially independent, traveling the world with Annabelle in tow, and occasionally sharing their experiences on their blog, Adventuring Along. Read on to see how they did it.