Some of the most successful people in business have had to overcome serious hurdles to define their futures.
Steve Jobs was humiliated and felt pessimistic about his future after he was fired from Apple, the company he co-founded. Hip-hop titan and judge of ABC's "Shark Tank" Daymond John, who had worked hard to escape poverty, hit a low point when he lost nearly all of the money he made and couldn't afford to heat his home.
Media mogul Oprah Winfrey battled the traumatizing mental effects of childhood abuse, and faced sexual harassment and racism as a young professional trying to break into TV.
All three, however, said that working through these hardships made them stronger.
"The greatest discovery of all time," Winfrey once said on her TV show, "is that a person can change his future by merely changing his attitude."
And sometimes, as Winfrey says, it's our own mindset that's blocking the path forward. According to behavioral economics professor and business strategist Keld Jensen, nearly every professional will face serious doubts about whether or not he or she can succeed and find happiness in their work life.
In his book, "Intelligence is Overrated," the behavioral economist identifies 100 of the most significant thoughts that hold people back from great careers, based on his own research and experience in corporate consulting.
He notes, however, that as compelling as these thoughts may seem, they aren't fact.
Here are seven of the most common thoughts that are holding you back, as well as how to push past them:
1. I don't have the credentials
"Sometimes lack of credentials is an obstacle," Jensen writes. "Mostly it is not."
By industry standards, Jensen may not have the 'necessary' qualifications to succeed. He does not hold a Ph.D.
And yet he is an adjunct professor at the highly-ranked Arizona State University Thunderbird School of Global Management. He guest lectures at several other institutions, and he runs his own business and corporate strategy firm.
Jensen isn't alone in coming into a great career through a side door. Consider Bill Gates, Jobs or Winfrey, all hugely successful college dropouts.
"If you lack 'proper' certification, but know you're actually well-qualified, stop at nothing to get yourself in the door," Jensen writes, adding, "Of course, if it's important to you, you can also invest the time and money to earn a degree."
2. I am not creative enough
If you're not in touch with your inner Picasso, don't worry.
"You don't need to be extremely creative to be successful," Jensen writes. What's more important is hard work and resourcefulness.
"If you haven't got the creativity for a particular project that requires it, team up with someone who does."
Also remember that creativity is often in the eye of the beholder: The animation icon Walt Disney was once fired for lacking creativity.
Research published in the Harvard Business Review shows that positive thinking on the subject can work: People who tell themselves they are creative are more likely to actually be creative.
3. I tried before, and I failed
While you may need to take a different approach this time around, Jensen writes, it's important not to lose your mojo.
"If someone or something has managed to program you into a lack of confidence, reprogram!" Jensen writes.
"Start telling yourself every morning that you're great at what you do," Jensen writes. "Do it while you're driving, before you go to sleep at night, and more."
Especially if you pair your self-talk with hard work, you'll start to believe you are capable after all.
4. I don't like to be led
Sometimes great thinkers feel stifled by a hierarchical work structure. But in many ways, having a boss can have its benefits.
"So you don't work well under someone else? I don't either," Jensen writes. "Want to know the truth, though? Sometimes being led is exactly what you need if you want to advance."
It's all about absorbing information.
"Think about it. Someone who has more experience can show you the way," he says. "You can profit from that experience and save yourself some major troubles, setbacks and failures."
5. I don't want to start something else that I'll never finish
Try flipping this notion around.
"If something is truly worth doing, do it," suggests Jensen. "Commit yourself."
Make it easier for yourself to succeed. Set frequent milestones you want to reach, he writes, and reward yourself once you get there. That will make each small goal, and the larger overall one, easier to achieve.
6. I don't deserve it
Jensen challenges you to consider the logic underpinning that thought.
"You don't just deserve things because you exist. You aren't just magically provided for," he writes. "You earn what you receive — with your intelligence, your creativity and your hard work."
Whether it's a job promotion or a raise that you're after, allow yourself to want it. Then allow yourself to savor your achievement.
"Never be afraid to enjoy the rewards of your success. Be sure you do make time to enjoy them."
7. I don't know what my passion truly is
Jensen admits that he struggled with this one for decades.
"I didn't find my passion until I was 30. Some never discover theirs," he writes.
To start figuring out what you love and want to do, the author recommends a practical endeavor.
"Go to the bookstore and just browse. Notice the section you gravitate toward," he writes. "You may be looking at a clue to where your passion lies."
Check out the rags-to-riches rise of self-made billionaire Oprah Winfrey.
This article is an updated version of a previously published article. Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank."