Successful people are inspiring, but not all of them achieved success the same way. Some knew what they wanted to do from a young age and focused on it, while some reinvented themselves, changing industries and careers. Some discover their full potential at a much later stage. But the end result is that they're now some of the world's extremely successful people.

But what exactly were these people doing when they were at the young and fresh age of 25?

1. Martha Stewart - Businesswoman, writer and television personality.

Stewart was a stockbroker for the firm of Monness, Williams, and Sidel, the original Oppenheimer & Co. She worked on Wall Street for five years as a stockbroker. Before that she was a model.

"There were very few women at the time on Wall Street … and people talked about this glass ceiling, which I never even thought about," Stewart said in an interview for PBS's MAKERS series. "I never considered myself unequal, and I think I got a very good education being a stockbroker."

Stewart left Wall Street to be a stay-at-home mother in 1972, but a year later she started a catering business.

2. Mark Cuban - Businessman and investor.


He graduated from Indiana University and moved to Dallas at 25. He started out as a bartender, before becoming a sales person for a PC software retailer. Cuban then got fired because he wanted to go close a deal rather than open a store in the morning. That inspired him to open his first business - MicroSolutions.

“When I got to Dallas, I was struggling — sleeping on the floor with six guys in a three-bedroom apartment,” Cuban writes in his book “How to Win at the Sport of Business.” “I used to drive around, look at the big houses, and imagine what it would be like to live there and use that as motivation.”

3. Arianna Huffington - Owner of Huffington Post, author, and syndicated columnist.

She was Arianna Stassinopolous before she married her then husband, Michael Huffington. At the age of 21, she met famed British journalist Henry Bernard Levin while on a panel for a quiz show. They soon fell into a relationship and he became her mentor while she wrote the book "The Female Woman," attacking the women's liberation movement, which published when she was 23.

Huffington spent the next few years traveling to music festivals around the world with Levin as he wrote for the BBC. Their relationship eventually ended because he didn't want marriage or kids. Huffington moved to New York City at 30, and later that year, her biography of Maria Callas was published, which she dedicated to Levin.

She told William Skidelsky at The Observer:

"[Levin] was my mentor. Our second date was to see 'The Mastersingers' at Covent Garden. Our first trip abroad was to Bayreuth to see 'Wagner's Ring.'"

4. Lloyd Blankfein - CEO and Chairman of Goldman Sachs.


Blankfein was an unhappy lawyer at law firm Donovan Leisure.

"I was as provincial as you could be, albeit from Brooklyn, the province of Brooklyn," Blankfein told William Cohen at Fortune Magazine.

He was a heavy smoker and occasional gambler at the time, and despite the fact that he was on the partner track at the firm, he decided to switch to investment banking, joining J. Aron at the age of 27.

5. Ralph Lauren - Fashion designer and businessman.

At 25, Ralph Lauren was a sales assistant at Brooks Brothers. Born Ralph Lifshitz in the Bronx, New York, he changed his name at the age of 15. He studied business at Baruch College and served in the Army until he was 24 years old when he left to work for Brooks Brothers. At 26, Lauren designed a wide European-styled tie, which eventually opened up an opportunity with Neiman Marcus. The following year, he launched the label "Polo."

6. J.K. Rowling - Novelist

Rowling was 25 when she came up with the idea for Harry Potter during a delayed four-hour train ride in 1990. She began her first book that evening, but it took her years to actually finish it. While working as a secretary for the London office of Amnesty International, Rowling was fired for daydreaming too much about Harry Potter, and her severance check helped her focus on writing for the next few years.

During these years, she got married, had a daughter, got divorced, and was diagnosed with clinical depression before finally finishing the book in 1995. It was published in 1997.

7. Jay-Z - Rapper, record producer, and entrepreneur.

Born Shawn Carter, he grew up in a housing project in Brooklyn, New York. He was known as Jay-Z at age 20, and in the next few years he appeared alongside various rappers but "remained relatively anonymous" until he founded the record label Roc-A-Fella Records at the age of 27 with two other friends. The same year, Jay Z released his first album, "Reasonable Doubt."

8. Marissa Mayer - President and CEO of Yahoo!


At 24, Mayer had just started her job at Google as its 20th employee and the company's first female engineer. She remained with the company for 13 years before moving on to her current role as Yahoo's CEO.

Mayer told VMakers in an interview, "During my interviews, which were in April of 1999, Google was a seven-person company. I arrived and I was interviewed at a ping pong table which was also the company's conference table, and it was right when they were pitching for venture capitalist money, so actually after my interview Larry and Sergey left and took the entire office with them."

And since everyone in the office interviewed you in those days, Mayer had to come back the next day for another round.

9. Warren Buffet - Investor and philanthropist.

Warren Buffet started out as an investment salesman in Omaha. In his early 20s, he worked as an investment salesman for Buffett-Falk & Co. in Omaha before moving to New York to be a securities analyst at age 26. That year, he started Buffett Partnership, Ltd., an investment partnership in Omaha.

Buffett told NBC that New York just wasn't for him, "In some places it's easy to lose perspective. But I think it's very easy to keep perspective in a place like Omaha."

10. Ursula Burns - Chairman and CEO of Xerox.

Burns started out as an intern at Xerox. She worked her way up throughout her 20s. She got a degree in mechanical engineering from the Polytechnic Institute of NYU, and later on, a master's from Columbia University.

Since then she's been a Xerox lifer. She started as an intern at age 22 in 1980 and joined full time a year later after getting her master's. She rose rapidly through the ranks, working in various product development roles before being named CEO in 2009.

"When I came to work at Xerox, I just chose to work. Somebody said 'how about this?' And I said OK, and I would go do that in the lab," Burns said in an interview for the PBS documentary, "Makers." "Then somebody said how about doing some business planning. Then I started leaning more towards larger global systems problems. And systems problems are the business."

11. Mark Zuckerberg - Co-Founder and CEO of Facebook.

Zuckerberg had worked on Facebook for five years by the time he hit 25. That year, in 2009, the company turned cash positive for the first time and hit 300 million users. He was excited, but said it was just the start, writing on Facebook that "the way we think about this is that we're just getting started on our goal of connecting everyone."

The next year, he was named "Person of the Year" by Time magazine.

12. Richard Branson - Businessman, investor, and founder of the Virgin Group.

Branson had already started the Virgin Records record label. At 20, he opened his first record shop, followed by a studio at 22, then launched the label at 23. By 30, his company had gone international.

The early years were tough, he told Entrepreneur: "I remember them vividly. It's far more difficult being a small-business owner starting a business than it is for me with thousands of people working for us and 400 companies. Building a business from scratch is 24 hours, 7 days a week, divorces. It's difficult to hold your family life together; it's bloody hard work and only one word really matters — and that's surviving."

13. Sheryl Sandberg - Businesswoman and COO of Facebook.

At 25, she graduated at the top of the economics department from Harvard and worked at the World Bank under her former professor, mentor, and future Treasury Secretary Larry Summers, and had gone back to Harvard to get her MBA, which she received in 1995.

She went on to work at McKinsey, and at age 29 was Summers' Chief of Staff when he became Bill Clinton's Treasury Secretary.

"It wasn’t really that long ago when I was sitting where you are, but the world has changed an awful lot. My section, section B, tried to have HBS’s first online class. We had to use an AOL chat room and dial up service (your parents can explain). We had to pass out a list of screen names, because it was unthinkable to put your real name on the internet. And it never worked. It kept crashing … the world wasn’t set up for 90 people to communicate at once online. But for a few brief moments though, we glimpsed the future, a future where technology would power who we are and connect us to our real colleagues, our real family, our real friends."

14. Eric Schmidt - Executive Chairman at Google.


Schmidt got his master's and Ph.D. at 27 for early work in networking computers and managing a distributed software development.

He spent summers working at Xerox PARC labs, which helped create the computer workstation as we know it. There, he met the founder of Sun Microsystems, where he had his first corporate job.

In his early years as a programmer he said, "all of us never slept at night because computers were faster at night."

15. Howard Schultz - CEO of Starbucks.


Before he started out in the coffee business, Howard Schultz was a Xerox salesman. His success at Xerox led him to be recruited by Swedish company Hammerplast, that made coffeemakers, at age 26.

While working for that company, he encountered the first Starbucks outlets in Seattle, and went on to join the company at age 29.

"I learned more there than in college about the worlds of work and business. They trained me in sales, marketing, and presentation skills, and I walked out with a healthy sense of self-esteem. Xerox was a blue-chip pedigree company, and I got a lot of respect when I told others who my employer was ... But I can't say I ever developed a passion for word processors."

16. Roman Abramovich - Business tycoon and owner of Millhouse LLC.

This billionaire had already set up and liquidated at least 20 companies. He was an orphan as a child and was raised by his uncle. By age 21, he entered the black market through money he had received from his wife's parents. His companies eventually became legal businesses in the early '90s, by which time he had already been involved with at least 20 companies.

At 26, he was arrested for theft of government property, and by the age of 35 became Governor of Chukotka in Russia. But he maintains he was innocent, saying, "There were problems with the banking system … at the time when the refinery discovered they haven’t got the money, whilst I was under arrest, they received the money and I was released."