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.

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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.

The Olsons graduated from college with a combined $30,000 in student loans to pay off — no small amount, but not as much as it could have been, thanks to the low tuition costs of their public, in-state college and assistance from relatives. But they lived frugally and made consistent payments, quickly watching that number shrink.

Enjoying the beach at Port Douglas, Australia (Joe and Ali Olson)

In 2007, Joe and Ali bought their Las Vegas condo at a steep discount. At the end of 2008 — amid the financial crises when housing prices were battered — they also purchased a rental property nearby and started trying to turn a profit. It didn't work out at first, and they took a financial hit.

Hiking El Camino de Santiago (Joe and Ali Olson)

"It seemed like a good deal because the price of the property was $120,000, and at the peak, it had sold just two years before for $360,000," Joe said. "But then the prices kept falling. And it kept falling in 2009 in 2010. And that property actually bottomed out being worth around $80,000. So we were under water on it, but we were still making money every month because the rent was higher than the mortgage payment by a decent amount."

Winter in Zagreb, Croatia (Joe and Ali Olson)

Joe and Ali weren't deterred, however. They kept at it, snatching up more properties during the market's downswing. Despite pulling in a combined $80,000 per year from teaching — plus extra income from summer school, tutoring, and other endeavors — the couple managed to live on just $20,000, so they were able to continually save and continue scooping up properties.

Meeting kangaroos and wallabees in Australia (Joe and Ali Olson)

"When we moved to Vegas to get teaching jobs after college, we moved into a 416-square-foot condo which only cost us under $500 per month for the mortgage and HOA (homeowners association) fees," Joe told Business Insider.

There, they lived frugally.

"We kept driving the same cars... We also ate at home, a lot. Eating out was rare, and a treat," Joe continued. "When we started acquiring rentals, friends and family would ask when we were going to move into one of these three-bedroom, 1,800 square feet places, rather than our tiny condo. But we were happy where we were. We never felt like we were depriving ourselves, because simple pleasures were enough."

They ended up with 15 properties in total. A third are concentrated in the Las Vegas area, but they own places in other markets as well, including Michigan, Vermont, and North Carolina. "A bunch of hedge funds came and started purchasing up rental properties and prices rose quite a bit," Joe said. "And so I started looking at other markets and investing in other areas."

Torre de Belem, Lisbon, Portugal (Joe and Ali Olson)

Eventually, the market flipped and the value of their properties began to rise quickly. Not only were Joe and Ali saving around 75% of their income, but the value of their rental assets caused their net worth to balloon rapidly. Eight years after arriving in Vegas, their combined net worth had eclipsed $1 million.

Meeting elephants near Chiang Mai, Thailand (Joe and Ali Olson)

How were they able to keep up with so many mortgages?

Joe explains: "Eventually we ended up with 15 properties, but only four with mortgages. $13,000-plus in gross rents each month, less $2,000 per month in mortgages."

Though they loved teaching, both Joe and Ali had other goals they wanted to pursue, including traveling and starting a family. "Teaching was great, but it was time to start new adventures," Ali wrote on their blog. So they decided to pack up and go for it.

Exploring the jungles of Thailand (Joe and Ali Olson)

"In 2015, after working for eight years, we quit and started to travel," Joe said. "We hiked El Camino de Santiago, a 500-mile walk, to kick off our adventures. We then bounced around Europe a bit, before settling in Istanbul for three months to have a baby, born January 2016. We've kept traveling since then, from Europe over to Australia and around Southeast Asia."

Touring Angkor Wat, Cambodia (Joe and Ali Olson)

Though they’re financially independent and retired from teaching, the couple still runs a few side hustles. They retain control of their rental properties from abroad, and Ali writes romance novels.

Prague, Czech Republic (Joe and Ali Olson)

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