Believing in your potential to succeed is vital. You have to believe in your ability -- believe you're capable -- in order to win.

But you also need to believe you can fail, and you have to allow your actions to be governed by that.

Talking to entrepreneurs each day, I've found the biggest internal crisis comes from what they see as a lack of belief. When business suffers, customers don't materialize or strategies fail, people often lose faith in themselves, question their mission and therefore give up. In short, they doubt.

Here's a secret: It's almost never a lack of faith that will sink you. It's a lack of doubt. More importantly, it's a lack of understanding of what faith and belief really are, to the point where you don't honor your doubts enough to embrace them.

You need to have faith, and part of that faith is serving yourself a shovelful of doubt, of questioning almost every decision you make. In fact, the bigger a person's doubt, the stronger his or her belief.

Look at theology, which peddles in faith and doubt as its stock and trade. Thomas Merton, the great inspirtational theologian, put it simply: "Faith means doubt. Faith is not the suppression of doubt. It is the overcoming of doubt, and you overcome doubt by going through it. The man of faith who has never overcome doubt is not a man of faith."

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Ponder that a moment. We tend to lionize the entrepreneurs who are singular in focus and purpose, who are so convinced of their mission that they pursue their business blind to the myriad consequences. We follow a narrative where we need to be so convinced of our path and our ideas that any doubt would derail the herculean effort it takes to succeed.

Yet, is it not better to give voice to our doubts, which, after all, stem from the same brain and heart that led us down this crazy, irrational, unsteady road we call entrepreneurship in the first place? The head and soul that convinced us to innovate, to try something new, to change minds, to help our communities and our customers also screams at us to go back to convention, to conform, to work quietly, meekly. Ignoring those screams often seems like the right thing to do for those of us who are abitious and bold. But it's actually a wrong approach, because we would be ignoring ourselves. And we alone know truly what's best for us.

Doubt can be a valued, constant companion, an emotional, nagging Sancho Panza we try to dismiss but know we could never live without. Doubt is our conscience. Doubt is our impulse to question all things, a reminder that scientific rigor holds more lessons than the meandering of our dreams. Doubt can be our enemy, but also our champion.

Doubt is our check and our balance. Without doubt, we'd be foolish in our pursuits, rather than strategic. Yes, giving shrift to our doubts isn't easy. You might cry yourself to sleep, assuming you're not up all night obsessing over Quickbooks. It means challenging yourself when it would be much simpler to let all the naysayers do that for you. It means flirting sometimes with depression and moodiness. It sometimes means more Hendrick's than tonic.

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But all of that is worth it, because, in the end, doubt will be your inspiration. Doubt will allow you to see your market more clearly. It will give clarity about business relationships, personal shortcomings, bad habits, the hellish outcomes of your otherwise good intentions. Doubt can inspire you to change or, in entrepreneurspeak, to pivot. When you think of it, the Lean Startup movement is based on the appreciation of doubt. You put your idea out there for the world to see, get instant feedback and make a decision of how to proceed. Sometimes you go forward. More often, you don't. It's a disrobing of your business before a room of customers with paper and charcoal in hand, ready to sketch their interpretation of your idea, your passion. One can't do that without confidence, nor a willingness to be open to your internal doubts and those of others.

To be clear, doubting yourself doesn't mean giving in to the temptation of giving up. That's not healthy doubt, but rather despondency and desolation. That can be just as destructive as blind faith. Rather, think of doubt as salt, which, in proper pinches, heightens all the flavors, but, in excess, dries up our mouth and sends our blood pressure through the roof.

In the end, people don't profit from the belief in their infallibility. The flaw in that conceit is that you skip the infinite opportunities to learn. When you think you know everything, you miss the joy of discovery that our world offers us each day. For the weekend poets, that could be the gorgeous flowerets in the sunlight shining, blossoms flaunting in the eye of day. To the entrepreneur, it's more likely to be that customer you hadn't considered, that product you never pondered, or the partner you had never approached.

So embrace doubt, and let it strengthen your belief and faith in yourself. Rather than ignoring that voice in your head, honor your doubts enough to validate the belief you have in your own capabilities to shine.

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