With graduation season in full swing, thousands of early 20-somethings are about to get a taste of the real world as they try to figure out what to do with their lives. Daunting as it may be, it's important to remember that even the most successful people have to start somewhere.
Take self-made billionaire Mark Cuban, the outspoken judge on "Shark Tank" and owner of the Dallas Mavericks, as an example. When he was 22 and a recent college graduate, he had to contend with major career setbacks: quitting one job and getting fired from another soon after.
Even as a kid, Cuban had a knack for business. At 12, he was selling garbage bags to buy a pair of shoes he liked. A couple years later, he was earning money by selling stamps and coins.
After transferring from the University of Pittsburgh at the end of his freshman year, Cuban attended Indiana University because it had the cheapest business school in the top 10.
There, he gave dance lessons to help pay for his tuition. "That endeavor soon led him to hosting lavish disco parties at the Bloomington National Guard Armory," according to Biography.com. Cuban graduated in 1981.
In an essay Cuban wrote for Forbes, he recounts moving back to his hometown of Pittsburgh after graduation to get a job at Mellon Bank. "Back then a lot of smaller regional banks still did everything on paper," he writes. "Mellon had a department that went in and converted them to computerized systems. That's what I did."
Even then the tech mogul, now 58, didn't want to lead an average life. "A lot of my peers at Mellon were just happy to have a job," explains Cuban. But he wasn't.
"I wanted to be more entrepreneurial. I took the initiative," he writes. "I used to send notes to the CEO of the bank. I once cut out a magazine story about how corporations could save money by withholding Social Security and sent it to him. He sent me a thank-you letter back."
I wanted to be more entrepreneurial. I took the initiative.Mark Cuban
Cuban also had a penchant for networking from a young age. "I started something called the 'Rookie Club.' I'd invite senior executives to a happy hour to talk to a group of younger employees in their 20s like me," he says.
But Cuban didn't stop there. "Then I went a little further. I started writing a newsletter. I did updates on current projects," he writes. "I tried to inject a little humor. I thought my boss would love me for doing these things."
Surprise: He didn't. In fact, Cuban believes his boss felt threatened. "I told him I was trying to help Mellon make more money. He told me I was never to go over him or around him, or he'd crush me," he continues. "I knew then it was time to get out of there."
Cuban moved to Indiana and then Texas, where he worked for a computer software company. After being fired from that job for closing a deal without the CEO's blessing, he started his own company: MicroSolutions. The business grew to over $30 million in revenue and in 1990 was sold to CompuServe for $6 million.
Cuban, a 32-year-old millionaire, decided to retire — for awhile anyway.
A few years later he cofounded a company called Audionet, which became Broadcast.com. During the dotcom boom, it grew to over 300 employees and in 1999 was acquired by Yahoo for $5.7 billion, making Cuban a billionaire at age 40.
The very next year, Cuban bought the Dallas Mavericks for $285 million.
Since then, Cuban has become a household name thanks to his regular appearance on "Shark Tank" starting in 2012. He's also made investments in a variety of start-ups, appeared on "Dancing with the Stars," and delved into film and television production. Three decades after getting fired as a 20-something, Cuban is worth an estimated $3 billion.
For new grads about to start their own careers, he offers this advice: "Never stop learning. Never stop grinding. Never stop loving every single minute of your life."
"Once you have found out what you love to do, there is only one goal," he writes. "How can you be the best in the world at it? It doesn't matter if you are a filing clerk, an athlete, an accountant or a bartender. All that matters is that you do whatever you can to be the best."
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Disclaimer: CNBC owns the exclusive off-network cable rights to "Shark Tank."