Entrepreneurship is hard, both physically and emotionally. Doubt, anxiety, despair--along the way, every entrepreneur struggles with those feelings.

So why are entrepreneurs willing to face the vulnerability, the emotional ups and downs, and the risk of public and private failure?

Easy. They have no choice. For entrepreneurs:

1. The voice in their heads is louder than every other voice they hear. Others may doubt. Others may criticize. Others may judge and disparage and disapprove.

You don't care. You see all those opinions for what they are: not right, not wrong, just data. So you sift through that data for the actual nuggets you can use. The rest you ignore.

Why? You may respect the opinions of others but you believe in your ideas, your abilities, your will and perseverance and dedication. You believe in yourself. And that makes you want to live your life your way and not anyone else's way.

2. They believe that how they play the game truly is more important than whether they win or lose. If you're an entrepreneur, you'd rather fail on your own terms than succeed on someone else's. You'd rather reach for your own future than have your future lie in someone else's hands. You feel it's better to burn out than to fade away.

Sure, you want to win. You're driven to win. But you want to change the rules, create your own playing field, and win the game you want to play--because winning a game in a way you're forced to play would still feel like losing.

3. They don't make choices--they create choices. Most people simply choose from Column A or Column B. Entrepreneurs glance at A and B and then often create their own Column C.

As Jon Burgstone says:

Every time you want to make any important decision, there are two possible courses of action. You can look at the array of choices that present themselves, pick the best available option, and try to make it fit.

Or, you can do what the true entrepreneur does: Figure out the best conceivable option and then make it available.

And that's why they often accomplish the inconceivable--because to entrepreneurs, that word truly doesn't mean what everyone else thinks it means.

4. They enjoy succeeding through others. Talent is obviously important, but the ability to work together, check egos at the door, and make individual sacrifices when necessary is the only way any team succeeds.

That spirit can only exist when it comes from the top.

And that's why entrepreneurs focus on the individual rather than the position, the team rather than the hierarchy, and most important, from gaining happiness and success from the happiness and success of others.

5. They don't need to be disciplined, because they can't wait to do all the things that bring them closer to achieving their goals. Discipline often boils down to finding a way to do the things you need to do. Entrepreneurs can't wait to do the things they need to do. They have goals and dreams, and they know every task they complete takes them one step closer to achieving those goals and dreams.

That's why entrepreneurs can have fun performing even the most mundane tasks. When there's a clear line of sight between what you do and where you want to go, work is no longer just work.

Work is exciting. Work is fulfilling. Work, when it's meaningful and fulfilling, is living. And that's why.

6. They don't want to simply gain a skill and then live a routine. Some people work to gain a skill or achieve a position so they can relax, comfortable in their abilities and knowledge. They've worked hard and are content. (That's not a bad thing; everyone's definition of success should be different.)

Entrepreneurs hate the contentment an acquired skill brings. Entrepreneurs hate the comfort an achievement affords. Entrepreneurs see acquired skills as a foundation for acquiring more skills. Entrepreneurs see achievements as platforms for further achievement.

Entrepreneurs pay their dues, and they want to keep paying more dues. They look at themselves in the mirror and think, "OK...but what have you done for me lately?"

And then they go out and do more.

7. They're fans of other entrepreneurs. Working for a corporation is often a zero-sum game, because personal success usually comes at the expense of others. If you get promoted, someone else does not. If you get an opportunity, someone else does not.

That's why, in a corporate setting, it's really hard not to begrudge the success of others--it's hard to be genuinely happy for a co-worker when you're really disappointed.

Entrepreneurs, on the other hand, love when others succeed. They know the pie is big enough for everyone. (Forget the current pie; they're out there trying to make new pies.)

Entrepreneurs see the success of other entrepreneurs as exciting and inspirational and as validation that creativity and hard work do pay off.

8. They're willing to start a movement of one. We all like to belong, to feel we're kindred spirits, and that's why some ideas quickly gain a following and why great ideas can become movements.

Joining a crowd is awesome. But every movement starts with one person who dares to stand up, alone, unprotected, and vulnerable, and be different: to say what others aren't saying, to do what others aren't doing--to take a chance and accept the consequences.

What makes entrepreneurs willing to take that risk?

9. They think, Why not me? Regardless of the pursuit, success is difficult to achieve. That's why we all fail sometimes. And when we do, it's easy to decide events were outside our control. It's easy to feel depressed and wonder, Why don't I ever get the opportunities other people get? or Why aren't my friends more supportive? or Why can't I catch a break?

In short, it's easy to think: Why me?

Entrepreneurs ask a different question: Why not me?

That's why entrepreneurs will open a restaurant in the same location where other restaurants have failed: They didn't succeed, but why not me? Entrepreneurs will start a software company with nothing but an idea: They may have deeper pockets and a major market share, but why not me?

Entrepreneurs don't assume successful people possess special talents or a gift from the startup gods. They see successful people and think, That's awesome, and if she can do that, why not me?

Good question: Why not you?

If you think about it, there is no real answer, because when you're truly willing to not just dream big but also to try incredibly hard, there are no reasons you can't succeed--at least none that matter to you.