Self-doubt is just part of being a professional. Facebook COO Sheryl Sandberg can give us some inspiration on how to put negative thoughts in their proper place.

By Amanda Pouchot

Facebook COO Sheryl Sandberg with Patricia Sellers at Fortune's 2012 Most Powerful Women summit in Laguna Niguel, Calif.

FORTUNE – At a recent work meeting, I caught myself saying the following words: "Well, this isn't a great idea, but what if we did …" and then I stopped. I remember saying such things during my first few meetings as a consultant at McKinsey & Company, but I thought surely by now -- as someone who had created and developed a company -- I would not succumb to that kind of preemptive self-doubt. But there I was, suggesting that my thoughts weren't worthy of discussion.

At a women's conference in 2010, Diane von Furstenberg responded to an audience member's question about how to behave confidently when you are not quite there with the following advice: "Fake it 'til you make it."

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Sheryl Sandberg, COO of Facebook (FB), echoed von Furstenberg's sentiment in a 2011 New Yorker profile. After listening to a college lecture on feeling like a fraud, she claimed, "I felt like that my whole life." Throughout her college years, Sandberg says, "I really fooled them." Addressing Barnard College graduates in 2011, she said that to this day she sometimes doesn't feel confident in herself: "All along the way, I've had all of those moments, not just some of the time; I would say most of the time, where I haven't felt that I owned my success."

Joanna Barsh, senior director at McKinsey & Company and author of How Remarkable Women Lead, says her biggest career challenge was getting out of her own way: "I was -- and am -- plagued by limiting fears … and because my sponsors were not versed in how to interact with such a creature, they took my 'no thank you' at face value and offered their opportunity to the next person -- a man who invariably grabbed it. It turns out that the challenge of getting out of my own way was the biggest one I ever faced."

At first I thought the concept of "faking it" was insincere, and that I would be lying to those around me. I was worried I'd be found out -- that they would discover that I don't have the skills to be doing what I am doing, or that I don't know what I am doing. I've come to recognize that these fears are irrational. But there are so many moments where I've let that little voice of doubt and insecurity take control.

Von Furstenberg, Sandberg, and Barsh make me feel less alone in falling prey to these negative thoughts. But just knowing that these powerful women had youthful moments of doubt is not enough: How did they actually learn to not listen to that feeling and get to where they are today?

Barsh suggests you should "remind yourself or find out what it is that you really want. Re-center yourself on possibilities ... Let go of non-mission critical tasks, accepting that you are not perfect and should not have that as a goal in mind." Sandberg's suggestion is similar: "Don't let your fears overwhelm your desire. Let the barriers you face -- and there will be barriers -- be external, not internal. Fortune does favor the bold, and I promise that you will never know what you're capable of unless you try," she told the Barnard audience.

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I'm a dreamer. I have big ideas for my company and for myself, but when it comes to action, I often hesitate, or worse, after I do something, I beat myself up over how I could have done it better. What I've come to learn is that the terrified feeling is part of being a professional, and especially part of being a female professional. I have learned to focus on what I can do one day at a time, ignoring the fear of failure. The opportunity to grow comes from taking risks, stretch assignments, and speaking up when you aren't 100% confident. There may be a few bumps, but slight embarrassment only leads to learning.

When I begin to doubt myself, I think about my motivations for doing whatever it is I'm uncertain of. I train myself to focus on what is possible and try to silence that voice in the negative voice in the back of my head.

Amanda Pouchot co-founded The Levo League with Caroline Ghosn.