In February 2015, Alex Trias, 53, and his wife Noki took their daughter Evie on a vacation to Lisbon, Portugal, and never looked back.

Trias, who retired from his career as a corporate tax attorney in 2011, lived with his family in Washington, D.C., where Noki was a nurse and their daughter was enrolled in school. Since retiring, Trias has worked for himself doing real estate and stock investing.

He tells CNBC Make It that the idea of retiring early came to him just two weeks into his career as a lawyer. "I quickly realized there was a shelf life to how long I was going to be able to keep up with the 90-hour workweeks my job demanded," Trias says.

"The result was that I saved fanatically and continued to do so for years."

After being in business for himself for just four years, the family had an investment portfolio that paid out enough dividends to live on — an average of $152,000 a year.

Just two days into their Portugal vacation, the family started planning a move to Lisbon. They toured apartments while on the trip and when Noki and Evie made the return trip home, Trias stayed behind a few extra weeks.

He found a two-bedroom, 1,300-square-foot apartment in Bairro Alto.

"It reminded me of Old San Juan and that's one of my favorite places on the planet," Trias, who is of Puerto Rican descent, says. "When you walk around there, it smells a lot like mahogany, the ocean and palm trees. In Lisbon, it's the same. I knew it would be awesome to live in a place like that."

A June report from Moving to Spain named Portugal the best country in Europe for retirement. It's one of the most affordable European countries because of its low cost of living.

On average, the cost of living, excluding rent, is almost 29% lower than in the U.S., according to SmartAsset. 

To retire in Portugal, U.S. citizens must apply for a residence visa. According to Global Citizens Solutions, the process is relatively straightforward and requires applicants to provide a valid passport, proof of income, health insurance and a criminal background check.

Trias says the easy process made the idea of living in Portugal even better.

The Trias family bought their Portuguese apartment for $533,554 (not including brokerage commission and taxes) and waited for Evie to finish middle school before moving to Portugal in June 2015 with just six checked bags.

Trias says he finds happiness just knowing he's living with his family in a country like Portugal: "I wake up and do whatever I want to do and I don't do a lot of anything that I don't want to do."

Alex has a habit of writing down in his journal what he plans to do for the day for enjoyment.

"The fact that I can get in the car and 20 minutes later be looking out over the ocean and the mountains is just priceless. I think my happiness comes from my decision to do unpleasant tasks while sitting at the beach," he says.

"I feel excited to get the day started and it always reminds me to every once in a while remember that we are living in Portugal, of all places."

While Alex keeps himself busy with their investments and freelance writing, Noki has found herself with enough free time to join a local tennis group and focus on her health. The couple goes on dates, and explores new things together like different activities and places around Europe and Portugal.

And now that Evie is in her last year of high school and looking at colleges outside of Portugal, the family is in a transitional period.

"There's still time to do something else. If we wanted to move to Thailand and volunteer at an elephant rescue center, we could do that still," Trias says. "I like to think we still have a few more chapters left in us."

DON'T MISS: Want to be smarter and more successful with your money, work & life? Sign up for our new newsletter!

Want to earn more and land your dream job? Join the free CNBC Make It: Your Money virtual event on Oct. 17 at 1 p.m. ET to learn how to level up your interview and negotiating skills, build your ideal career, boost your income and grow your wealth. Register for free today.