A couple who quit work at 43 to travel Europe on $18,000 a year share their best advice for retiring early

Reaching financial independence before typical retirement age is an increasingly popular trend.

For Jason and Julie Buckley, retiring last year at age 43 meant relinquishing the stress of the corporate world and jumping into a life of full-time travel.

Shepherded by meticulous spreadsheet estimates and years of tracking their pennies, the British couple retired with about £30,000 (~ $36,800) in cash savings and set a modest retirement budget of £15,000 (~ $18,400) a year, Jason told Business Insider in an email.

The rest of their net worth is invested in rented-out residential property, private pensions, and investments including ETFs and bonds.

For the past 10 months, the Buckleys have been touring Europe and North Africa in their motor home, which enables them to visit expensive countries "for a fraction of the cost."

"We developed a strategy to avoid living off savings. In theory, and in practice so far, our savings will increase over time," Jason said. Currently, the couple lives off of cash flow from investments - rental income, dividends, and interest - as well as advertising and book sales on their travel blog, which they spend just two hours a day maintaining.

If you're aiming to achieve early retirement yourself, Jason says, "You're most likely going to be swimming against a very strong tide of opinion! If you're infected with an insatiable desire to do it, then be confident you can do it."

They suggest starting with educating yourself financially and putting your plan on paper, tracking spending and cutting all unnecessary costs, and investing.

"As your costs come down, and income from your investments gets re-invested in more investments, at some point you will experience the bewildering and joyful moment when your wealth starts to spiral upwards," Jason said. "At that point your freedom is all but inevitable."

Access a test copy of the Buckleys' spreadsheet to track your own viability for early retirement. Check out their blog Our Tour for more advice, tips, and information on reaching financial independence.