A flight attendant saved 25 times her cost of living and plans to retire at 44. Here's how she did it.

• Bianca DiValerio is a flight attendant who has achieved financial independence through the FIRE (Financial Independence Retire Early) method and writes a blog called Miss Mazuma.
• She calculated her annual expenses to be around $24,000, then saved 25 times that amount to become financially independent — around $600,000.
• DiValerio credits property ownership, nearly doubling her work hours, shopping in bulk, and curbing unnecessary spending with helping her achieve her goal.
• She plans to continue working part-time until 2022, when she can retire from her airline with full benefits.
• Visit Business Insider's homepage for more stories.

Like many working people, Bianca DiValerio is biding her time until she can retire. But unlike many working people, she actually has enough money to do it.

At 40 years old, DiValerio has achieved financial independence, defined as the ability to live comfortably without having to work, through a method known as FIRE: Financial Independence Retire Early. After 18 years as a flight attendant, she's just about ready to embrace life as a retiree.

Her journey to financial independence began with a post on the personal finance blog Mr. Money Mustache called "The Shockingly Simple Math Behind Early Retirement." According to Mr. Money Mustache, the key to retiring early is minimizing expenses and saving as much of your income as possible.

Your "retirement number," the amount of money you need to save in order to live in retirement, is 25 times your annual spending

Read more: How to retire early so you can work, travel, and relax on your own schedule

"When I first found out about it, I was like 'What are my expenses?' I didn't even know at that time," DiValerio said. "I knew what I was making every month, and I've tracked my net worth since 2012 for no reason other than I was a money nerd, but I didn't ever think about tracking my expenses."

In 2016, she began tracking every cent. First, she experimented with making drastic cuts to see just how little she could live on. She canceled her cable service, stopped going to restaurants, and shopped in bulk. Her expenses that year totaled $18,278.

"Once I learned that formula of early retirement, to me, spending $18 on a glass of wine versus spending $18 on a box of wine at home and having your friends over made way more sense," she said. "You're still able to do the same things, you just kind of change a little bit of the facets to them."

In 2017, she decided to spend the way she normally would and compare the results. That year, her expenses added up to $23,292, and she worked off of that number (rounded up to $24,000) to set her FIRE number goal.

She set out to save 25 times her annual expenses of $24,000 to reach her retirement number of $600,000 — and she did it

There are a few ways she managed to reach her goal so fast.

For one thing, she doesn't pay rent. Up until the housing market crash in 2008, DiValerio invested in real estate. She still owns a few properties, but she realized she needed a new plan after a series of short sales. Despite the setbacks, she was able to keep living rent-free as she saved for her retirement number.

In her work as a flight attendant, DiValerio earns hourly wages. By nearly doubling her hours as she worked to "aggressively" save money, she nearly doubled her income, as well.

She doesn't have children or any major health issues that would run up large bills. She also learned to recognize the difference between wants and needs when it came to her spending.

"A lot of people walk into Target these days and have no idea why they're walking out with a $250 bill," she said. "Half of the things they just bought were things they didn't even know existed two minutes before ... and all of the sudden it becomes a need instead of a want."

Even though she has enough money to retire now, DiValerio plans to keep working "very, very part time" until 2022, when she can retire with full benefits from her airline

While she doesn't spend mindlessly on impulse purchases anymore, she's happy to have a long retirement ahead of her. She's working on fixing up one of her properties, a tiny home inside a refurbished caboose in Lake Geneva, Wisconsin. She walks dogs for a side hustle. And she shares her story as a featured speaker at events for the FIRE community and on her blog, Miss Mazuma.

"Everyone talks about 'spoiling yourself,'" she said. "You can do that all day, but I'd much rather have the time off of work and get to be around my friends and family and do things that I'm passionate about."

• Read more:
• My husband and I live in Seattle and save almost half our income so we don't have to work by 40. Here's what we spend in a typical week.
• 8 people who retired before age 45 reveal how the decision changed their money habits
• There are only 3 things you need to focus on if you want to retire early
• These 20 questions can help tell you how close you are to becoming financially independent

FOLLOW US: INSIDER is on Facebook

Join the conversation about this story »

NOW WATCH: Animated map shows how cats spread across the world