At one time or another, most of us have fallen prey to imposter syndrome. No matter how qualified we may be or how hard we work, there's that nagging voice in our heads that suggests that maybe we're frauds who are undeserving of our accomplishments, our promotions, or even our jobs.

However, we can take some comfort in the fact that many of the most high-achieving people of our time suffer from imposter syndrome too, from Tina Fey to Sheryl Sandberg.

We're often a lot more brighter and talented than we believe, but sometimes we need to be reminded. Here are eight surprising signs that you're a lot more successful than you (or that pesky voice of doubt) may know.

1. You use your time wisely

Successful people don't waste their own time. This could mean getting up early, or spending time with your kids, or just taking care of all the little errands cluttering your schedule. If you actively work to accomplish your daily goals, instead of watching reality television, you've already mastered one of the most crucial personal and professional skills.

According to Thomas Corely, financially successful individuals spend only an hour or less watching television and spend more time focusing on their daily to-do lists and reading.

2. You don't let failure discourage you

If you focus on your successes, however big or small, instead of obsessing about your failures, you're more of a winner than you realize. Too often in life, people's goals get derailed when they focus on their setbacks. But if you have the mental fortitude to pivot in a more productive direction when things go wrong, you're setting yourself up for success.

Take investor and Shark Tank host Mark Cuban, for example. When he got fired from a small computer store, he used that failure to his advantage. He took his skills in tech and salesmanship and launched his massively prosperous entrepreneurial career. If you set out to make your own luck, the possibilities are truly limitless.

3. You go the extra mile

Doing the bare minimum might allow you skirt by in your career, but it probably won't make you stand out or help you catch your big break. But if you're the kind of person who makes an effort to go above and beyond what's expected of you, that's a surefire sign that you're a hard worker who deserves that promotion or raise, no matter what your voice of doubt says.

Entrepreneurs like Elon Musk get ahead of the competition by clocking in more hours than your average business person. While you probably shouldn't work 80 hours a week like Musk often does, you can apply this trait on a smaller scale to get ahead in life.

So whether you work a little overtime, or help a new hire learn the ropes, or brainstorm ideas to help your company grow when it's not required of you -- all of this shows your dedication to your team and your company. Hard work will get you noticed.

4. You're an attentive listener

Being able to take in what your employees, family, or friends tell you is an undervalued skill, but being a good listener can open doors and opportunities for you. For billionaire and investor Richard Branson, being a good listener and good leader go hand in hand. "Great listeners are often terrific at uncovering and putting in place strategies and plans that have a big impact." If you use this gift to your advantage, you'll be able to address problems effectively and improve your working and personal relationships.

5. You're a constant learner

Many people believe education stops after graduation, but if you've cultivated the habit of being a constant learner, you're already ahead of the game. Reading educational books and biographies or listening to an informational podcasts might seem like small-time activities, but they can actually have a profound effect on your chances of becoming successful.

Some of the world's greatest innovators and entrepreneurs - from Bill Gates to Oprah Winfrey - started from humble beginnings, but they attribute their rise to the top to investing in continued education. Attending seminars and conferences in your field or taking online classes is another indicator that your sharp and reflective mind is bound for great things.

6. You welcome constructive criticism

Taking in constructive criticism is not only an essential professional skill, it's also an important opportunity to grow as a person. People who welcome these kinds of honest evaluations, understand that no matter how self-aware you are, sometimes you need outside input. Accepting the reality that no one is perfect and that there's always room for improvement is a trait many influential and powerful people share and thrive off of.

A study conducted by PsychTests revealed that employees who react defensively to constructive criticism are more likely to be unsatisfied with their jobs and have poorer performance ratings. Successful people take honest feedback in stride, and they don't let it ruin their job outlook or work performance. They do the opposite.

7. You enjoy helping others

Success isn't all about growing your financial assets or status, but making your day to day life meaningful. If you love assisting people or providing value to clients and customers, that's an excellent way to achieve that kind of success. Albert Einstein, one of the most accomplished and influential scientists of all time, once said "Try not to become a man of success, but rather try to become a man of value."

8. You take care of your health

Taking care of your mental and physical well-being is another indicator that you're more successful than you think you are. It takes a lot of discipline to routinely exercise, meditate, eat right, or participate in other healthy lifestyle practices when the throws of daily life often work against us. That discipline and ability to form healthy habits can translate to your work ethic and your ability to accomplish your life goals.

Many of the world's most famous entrepreneurs find a direct correlation between working out and their productivity. Take it from the CEO of MWI, Josh Steimle, who makes exercise one of his biggest priorities. "If exercise stops, then my health goes downhill. With the loss of physical health my productivity at work goes down ... I've learned firsthand that excellence in one area of my life promotes excellence in all other areas of my life. Exercise is the easiest area of my life to control."

Do you have any ways to beat self-doubt and realize success? Share them with me on Twitter!