It's one thing to make millions, but quite another to keep them--or to grow them. The good news is that the pre-recession keeping-up-with-the-Joneses/Kardashians lifestyle that many Americans chased is over. You have to plan and save to get ahead. You have to work to decrease your debt. Being frugal is trending now, from thrifting as a fashionista skill staple to actually shopping at farmers' markets as a way of saving money and eating healthy.

It doesn't matter whether you've already earned your first million or that's a goal you have yet to achieve. If you start practicing a frugal lifestyle now, you'll stay there longer or get there faster and maybe even enjoy it more. Here are some of the best tips on frugality from current millionaires.

1. Shailene Woodley on thrifting

"In my personal life, I only buy used clothes, so thrift stores, trade-in stores, vintage stores, friends' closets. Sometimes it's hard to find a good pair of used shoes and jeans, but 97 percent of my wardrobe is used." Thrifting doesn't just save you a ton of money; it's also kind to the environment. You're not supporting the manufacturing (and subsequent carbon footprint) of a brand new product or the location and transportation costs (both financial and environment-impacting) to get it to your front door.

2. Gilbert Gottfried on showboating

Notorious for his frugal habits as well as some unfortunate opinions expressed in public, Gottfried has been wealthy and famous for decades. That hasn't changed his mindset, though. He knows that wealth isn't enjoyed by showing it off. "I'm not one of those people who could show you my collection of vintage cars," he says. Instead, he's invested in his children's future, lives a comfortable but "normal" life with his family, and continues to work while letting his money work at the same time.

3. Vivienne Westwood on using what you have

"I'm frugal. I'm not a very acquisitive woman. I never waste food. If you prepare your own food, you engage with the world, it tastes alive. It tastes good." Waste not, want not? It's still very sage advice revered by one of the world's best-known designers. Not only is wasting any product, be it food or makeup, flushing your money down the drain; it also doesn't respect the process. In Westwood's case, preparing, savoring, and completing your own meals isn't just frugal; it also shows respect to everyone involved, from the farmers to the manufacturing workers.

4. Joe Bastianich on saving

"Being frugal, conscious of making money, is not a negative thing. That sensibility of creating value and finding value and reinvesting in those customers is what separates great restaurants from the average ones." A main goal in life (and in finance) is to create value--as much as possible. This restaurateur equates making money with valuing it, his customers, and his business.

5. Tyra Banks on money management

"When I was young, my mom would give me my allowance, and I'd peel off a little each week and have some to spare." If you're not doing this with your paycheck, start now. Banks says she's always been frugal--and still is. The rush of spending like there's no tomorrow is a temporary one, and can lead to a downward spiral. The savvy millionaire (or millionaire-to-be) knows how to budget, how to save, and the importance of tucking funds away.

Some of the "best" frugal advice involves embracing what's easiest and best for you. Some people get a high over thrifting. For others it's cutting coupons or figuring out where the absolute lowest cost items are in neighborhood stores. Some "frugalistas" might have a penchant for gardening and create their own harvest, while others enjoy the intimacy of tiny-house living.

There's no one or best way to become frugal--but it's crucial to keep working toward that mindset and lifestyle. It doesn't mean suffering or not enjoying your money. It's a survival tactic, and one that can serve you well should the worst-case scenario ever pop up. A lot of people were badly surprised by the recession and forced to sell their McMansions and BMW 3 Series. However, the savviest of millionaires survived, safe with their nest eggs and already honed frugal habits.