There are many reasons why you think you won't succeed.
More precisely, there are about 100, according to behavioral economics professor and business strategist Keld Jensen.
In his book, "Intelligence is Overrated," Jensen explores the 100 most significant ideas holding people back from great careers, based on his own research and experience in corporate consulting.
However compelling they seem, those ideas are often just excuses.
Here are seven of the most common thoughts that are holding you back, as well as how to push past them.
"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 PhD.
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 Steve Jobs, Bill Gates, or Oprah Winfrey, all wildly 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."
If you're not in touch with your inner Picasso, don't worry.
"You don't need to be extremely creative to 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.
And research featured 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.
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.
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? Sometime 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."
Try flipping this notion around. "If something is truly worth doing, do it," suggests Jensen. "Commit yourself." And make it easier for you 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.
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."
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 very practical endeavor.
"Solution: 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."