4 phrases to give up if you want to get more out of your career

You can probably think of 100 reasons why you won't succeed, according to behavioral economics and negotiation expert Keld Jensen.

In his book, "Intelligence is Overrated," Jensen explains that many successful leaders and entrepreneurs have serious anxiety about their future. But according to his research, the most successful people are the ones who find a way to work through their fears.

If you're looking to make a change in your career and find yourself gripped by self-doubt, take a look at these are four common things professionals tell themselves when they're scared — and why they're probably wrong:

Brian Wong, is a 26-year-old CEO, will be the first to admit that you don't necessarily need skill or talent to become successful. What you do need is a strong work ethic.

"It's so easy for us to put up mental barriers, to make excuses to be lazy," Wong told CNBC. "But there's obviously a huge opportunity for us to not do that, which is what I think differentiates the haves and the have nots."

After skipping four years of school and graduating from college at age 18, Wong founded a mobile advertising company called Kiip. The company has more than $32 million in venture capital funding and works with clients like Unilever and BMW.

"Being on time, working hard — most of the things that can catapult you to success actually don't take a lot of skill or talent," he said.

In fact, talent by itself is only part of the reason people achieve success, according to psychologist and MacArthur "Genius" fellow Angela Duckworth.

According to Duckworth, author of the bestseller "Grit: The Power of Passion and Perseverance," success comes more from practice and hard work.

"You can grow your grit from the inside out," she writes.

Melody McCloskey, co-founder of on-demand beauty appointment service StyleSeat, once thought her lack of experience in technology would prevent her from achieving success. Instead of listening to her self-doubt, she reached out to people in the industry and asked for coffee meetings and professional advice. It worked.

"Everyone can think of a million reasons why you shouldn't do it," she says "'I don't have the time,' or 'I'm not smart enough' or 'I haven't done this before.'"

But the reality is, that's no excuse to not try.

And if you haven't broken into an industry yet, don't assume you don't have the relevant skills. For example, a person who has worked as a waiter has great multi-tasking and customer service skills. A camp counselor who works with children, parents and other counselors from different backgrounds has great people skills. If you can market yourself in the right way, you can convince others of your potential for success.

You can also take on new projects at your current job that will teach you those skills. Even speaking with a professional with a job you'd love to have can be extremely rewarding and point you in the right direction.

Never underestimate the power of a cold email or LinkedIn message.

That's how Google executive Peter Roper landed his job with the tech giant. The initiative he showed in reaching out to the right managers impressed his future boss.

"Personally reach out to the hiring manager or person in charge of your department there," he tells CNBC.

Taking this extra step shows the hiring manager that you are willing to devote time and energy to contacting them, which helps you stand out from the crowd.

Katia Beauchamp, co-founder and CEO of Birchbox, used cold emails to break into the beauty and technology industries. She credits a specific cold email strategy with a range of opportunities, new gigs, new professional contacts, and even the chance to be in touch with Steve Jobs.

You certainly shouldn't ignore this worry thought because going broke is not the path to success. At the end of the day, you do need to pay rent and have a source of income.

However, there are ways to make your goals work. Consider taking on new responsibilities at work that align more with your interests, so that you enjoy what you have more. Ask for a raise if you feel or know you are being underpaid. Seek advice from friends or find a mentor.

If money is a real issue, consider your options. For example, young professionals can save thousands of dollars by living with their parents. And everyone can get smarter about budgeting. Kyle Taylor, a young self-made millionaire who used to be broke, used a few money-saving strategies that saved him thousands.

"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."

Soon enough, he says, you'll start believing it.

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