Being a millionaire or billionaire -- especially a self-made one -- usually requires being disciplined about saving and spending, as well as investing wisely. Although the super-rich can splurge on lavish vacations and fancy cars, some eschew a luxurious lifestyle for one that allows them to maintain their wealth over the long term.
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See Our List: 100 Most Influential Money Experts
Kristen Bell: Take Advantage of Coupons When Shopping
Net worth: $40 million
"Frozen" star Kristen Bell still clips coupons despite her multi-million-dollar wealth.
"I almost exclusively shop with coupons," she said on "Conan," sharing that her personal favorite place to shop with coupons is Bed Bath & Beyond. "It's the best one because they've got 20% off, and if you go and buy a duvet or an air conditioner or whatever, you could be saving upwards of $80."
Sara Blakely: Create and Maintain a Nest Egg
Net worth: $1 billion
Spanx founder Sara Blakely kept her day job while starting her shapewear company to make sure she'd be able to maintain a healthy nest egg.
"It's really important to save money and create a nest egg, become comfortable for yourself with what the nest egg is, and don't touch it," she told Business Insider. "Leave it there. I always had a portion of my paycheck put into savings, and that was an easy automatic way ... I didn't quit my job until I'd already landed Neiman Marcus and Saks Fifth Avenue. I was so careful, I [worked on Spanx] at night and on the weekends because I didn't not want to have income coming in."
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Warren Buffett: Think of Investing as a Long-Term Strategy
Net worth: $113 billion
Billionaire investor Warren Buffett isn't a proponent of active stock trading.
"When we own portions of outstanding businesses with outstanding managements, our favorite holding period is forever," he wrote in his 1988 Berkshire Hathaway shareholders letter. "We are just the opposite of those who hurry to sell and book profits when companies perform well."
Grant Cardone: Save $100K and Invest the Rest
Net worth: $600 million
Grant Cardone is a self-made millionaire, author and sales training expert. He recommends hitting a lofty savings goal -- $100,000 -- and then investing any money earned after you hit that amount.
"You need to prove to yourself that you can go out and get money," he wrote in a 2018 post for CNBC. "Saving $100,000 shows that you have an ability to make money and then to keep it. Most people can't do either of those things. Once you can earn and save, then you can start building wealth."
Mark Cuban: Don't Live Beyond Your Means, Even If That Means Living Like a Student
Net worth: $5 billion
Investor and "Shark Tank" star Mark Cuban believes that overspending can be an unnecessary cause of stress, and he advocates for living like a student if that's all you can truly afford.
"Your biggest enemies are your bills," Cuban wrote in a 2009 blog post. "The more you owe, the more you stress. The more you stress over bills, the more difficult it is to focus on your goals. The cheaper you can live, the greater your options."
Bethenny Frankel: Stay Out of the Red
Net worth: $80 million
Before she was the head of the Skinnygirl empire, "Real Housewives of New York" star Bethenny Frankel was a struggling 30-something who had racked up $20,000 in credit card debt. Her No. 1 money rule is to make sure you have enough saved to pay off all your bills.
"You can't put yourself in a position where, if the s--- hit the fan, you couldn't pay all of your bills at one time," she said. "If the world came to an end, I would be able to pay for everything. I might not be left with much, but I can afford what I have."
Sarah Michelle Gellar: Before You Make a Major Purchase, Sleep on It
Net worth: $30 million
Sarah Michelle Gellar has been a successful actress for decades -- and she has the net worth to prove it -- but she doesn't impulsively buy whatever she wants.
"I don't like making big purchases," Gellar told CNBC. "I will go back and stare at a leather jacket for a couple days before I even purchase it."
Beyoncé Knowles: Be an Independent Woman
Net worth: $500 million
Beyoncé Knowles doesn't just sing about independent women -- she is one. Knowles is married to one of the richest rappers in the world, but she's a mega success in her own right and thinks all women should be financially independent, too.
"You know, equality is a myth, and for some reason, everyone accepts the fact that women don't make as much money as men do," she said in the HBO documentary, "Life Is But a Dream." "I don't understand that. Why do we have to take a backseat? I truly believe that women should be financially independent from their men. And let's face it, money gives men the power to run the show. It gives men the power to define value. They define what's sexy. And men define what's feminine. It's ridiculous."
Ashton Kutcher: Invest In What You Know
Net worth: $200 million
Actor and venture capitalist Ashton Kutcher has a simple strategy for choosing his investments.
"Invest in the things that you know," he said on "Chelsea." "If you drink beer all the time -- if you go to microbreweries and you try all kinds of them -- you probably know which ones are the best, and my advice is always to invest in what you know."
Spike Lee: Don't Be Afraid To Ask Others for Money
Net worth: $50 million
Asking others for help funding a project or business you are passionate about shouldn't be a shameful thing. Oscar-nominated director Spike Lee told Wealthsimple that he's never afraid to ask for funding when he's working on a film he truly believes in. He also said to not be deterred when people continually say "no" when you ask.
"It only takes one yes," Lee said. "No matter how many people say no, you only need that one yes and you're off and running. You can't let the nos defeat you. Because that's all it takes -- just one yes."
Kevin O'Leary: Don't Buy (or Lease) a Car
Net worth: $400 million
Personal finance expert and "Shark Tank" investor Kevin O'Leary has said that buying a car -- or even leasing one -- is a bad use of your money.
"Cars cost a fortune in maintenance and insurance and just the amortization, which means as they go down in value, you're losing money," he told CNBC.
He recommends using public transportation or a ride-sharing service instead. And he practices what he preaches. O'Leary said that when his last lease was up, he returned the car to the dealer and left without getting a new one. He now relies on Uber and Lyft to get around.
Suze Orman: Find Pleasure in Saving Money
Net worth: $75 million
Suze Orman wants everyone to get "as much pleasure out of saving as you do spending," she told CNBC. Orman believes the key to saving more money is to shift your thinking from saving being "a real downer" to "feeling that it's great." Orman said that even though she is "a seriously wealthy woman," she gets joy out of saving money on groceries by using coupons.
"So the question isn't, 'When can you start enjoying the money that you saved?' My question back to you is, 'When do you start enjoying the process of saving?'" she said. "If you did that, you'll find that you don't even care about spending money anymore."
Chris Reining: When It Comes To Saving, Start Small
Net worth: N/A
Chris Reining was able to retire in his 30s as a millionaire thanks to his smart saving habits. Reining recommends cutting small costs first before making any drastic lifestyle changes when you're trying to save.
"I know there are some people out there that say you shouldn't worry about the $5 latte, but the more I think about it, cutting out the $5 latte was a good place to start," he told CNBC. "Because if you try to downsize your house, get rid of all your cars and make all of these drastic changes, it's so overwhelming and you're not going to do any of it."
After cutting out his lattes, Reining stopped going out for lunch, which saved him about $15 a day, and next cut out his costly flying hobby, which he was spending $1,000 a month on.
"The small changes will lead you to be able to make the big changes," he said.
Tony Robbins: Use Compound Interest To Build Your Wealth
Net worth: $600 million
New York Times best-selling author Tony Robbins wrote on his blog that "compound interest is perhaps the most powerful tool in your investment arsenal." Robbins recommends putting aside a portion of each paycheck into an interest-earning investment, such as a high-yield savings account, index fund or stocks.
Ed Sheeran: Give Yourself a Monthly Allowance
Net worth: $200 million
Singer Ed Sheeran stashes most of his income in savings, and limits his spending money to a monthly allowance.
"[I use] my Barclays student account," Sheeran told the Irish Examiner. "I've not upgraded because I don't spend much money. If I had all my money in one account I would spend all of it, so I get an allowance."
Oprah Winfrey: Find a Job That Doesn't Feel Like Work
Net worth: $3.5 billion
Oprah Winfrey held jobs as a babysitter and a five-and-dime store employee -- jobs she hated -- before landing a job she loved at 17, working at a radio station for $100 a week.
"I would have done it for free," she wrote on Oprah.com. "And that's when I made my peace with money. I decided that no matter what job I ever did, I wanted that same feeling I got when I first started in radio -- the feeling of, 'I love this so much, even if you didn't pay me I'd show up every day, on time and happy to be here.' I recognized then what I know now for sure: If you can get paid for doing what you love, every paycheck is a bonus."
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