Becoming wealthy and staying that way takes a certain level of discipline. Sure, an occasional splurge won't put you in the poor house, but frequent frivolous spending on things that aren't necessities can quickly erode hard-earned gains.

The frugal habits necessary to achieve financial success and maintain it are often simple lessons learned early on. In this slide show, meet 10 entrepreneurs, business leaders and famous faces, including Google's David Cheriton, former professional boxer Laila Ali, the "Oracle of Omaha" Warren Buffett and retired NASCAR racer Danica Patrick, whose modest lifestyle habits -- from clipping coupons to clipping their own hair -- has helped them maintain vast fortunes.

As Knight Kiplinger wrote in his classic column The Invisible Rich, "the biggest barrier to becoming rich is living like you're rich before you are."

Learn more about the cost-cutting moves that help make these successful millionaires and billionaires who they are.

Danica Patrick

Photo by HHP/Harold Hinson

Age: 36

Estimated net worth: $60 million

How she struck it rich: NASCAR driver

Frugal habit: Makes her own meals while traveling

The recently retired NASCAR driver keeps costs in check even when she's on the road by cooking. "I love to cook. While it can sometimes be hard to have all the right ingredients when I'm on the road, I love stopping by local farmers markets and cooking as often as I can. The food I make is much healthier than always eating out at restaurants, plus it's a great way to save money," Patrick says.