The smartest choice one CFO ever made with her money is something anyone can do

Even the wealthiest, most successful people have to start somewhere.

"Every master was once a disaster," writes self-made millionaire T. Harv Eker in "Secrets of the Millionaire Mind." "No one comes out of the womb a financial genius. Every rich person learned how to succeed at the money game."

For Ashley Fieglein Johnson, chief financial officer of online investing platform Wealthfront, it all started with a simple habit anyone can establish: living below your means.

"I never spent to the level I was earning," she told Business Insider. "I always stashed away bonuses and part of my checks into investment accounts and savings accounts."

This lifestyle allowed her to take calculated risks, a quality that self-made millionaire and author Steve Siebold says distinguishes the most successful people from the rest of us.

"The few instances where I did go 'underwater' were the times when I was investing in business, real estate, or other similar opportune investments," she explains. "I could afford to participate in these types of ventures because I always had savings to fall back on."

Johnson isn't the only successful person living below her means - even some of the world's wealthiest use this strategy. There are a surprising number of frugal billionaires who choose to save or give to charity, rather than drop their money on jets, yachts, and mansions.

Take Warren Buffett, for example, who lives well below his means in the Omaha, Nebraska home he bought for $31,500 more than 50 years ago.