(Editor’s note: Scott Edward Walker is the founder and CEO of Walker Corporate Law Group, PLLC, a law firm specializing in the representation of entrepreneurs. He submitted this column to VentureBeat.)

I have provided legal counsel and assistance to hundreds of entrepreneurs over my 15-year career. A recurring question among those clients has been ‘Why do some entrepreneurs make it, while others fail?’

I’ve given this issue a lot of thought. Obviously, there are a lot of variables that contribute to success, including lady luck.  But, in my mind, there are three characteristics that stand above the rest: guts, desire and passion.

Guts.  The entrepreneur world is not for the timid.  You have to have the guts to pull the trigger, to quit whatever you’re doing and to jump into the abyss (and believe me, this is easier said than done).  Most people just talk; few execute.

Guts is quitting Harvard, like Bill Gates and Mark Zuckerberg did.  (Picture that phone call to their parents: “Hey Mom, Hey Dad, I have some good news, I’m quitting Harvard…”).

Guts is quitting a lucrative job on Wall Street, like Jeff Bezos did.  He was Senior Vice President at D. E. Shaw (the youngest in the firm’s history), and he had the fortitude to resign, pack up his car, drive cross-country to Seattle and launch a bookstore out of a garage.

Guts is selling everything you own to raise money for your new venture, like Tony Hsieh did.  He sold everything (including his loft in San Francisco) — everything that was left from his $40 million exit from LinkExchange — and put the money into Zappos.

Entrepreneurship can be a lonely, painful path, and it takes a lot of determination to succeed. It’s knowing how heavily the odds are stacked against you – and believing enough in your idea to risk everything.

Desire.  How badly do you want success? How much are you willing to sacrifice?

Great entrepreneurs make their venture the number one priority in their life; in short, they become obsessed.

Mark Cuban, the billionaire owner of the Dallas Mavericks, said he didn’t take a day off for seven years when he launched his first venture, MicroSolutions.  Instead, he spent all day banging on doors selling, and at night he would pull all-nighters reading everything he could about computers – teaching himself.  Working by day, learning by night.  That’s the kind of desire that you need.

It’s another example of easier said than done. If you’re married or have children, it’s even harder. And if you’re single, it means forcing yourself to stay focused while your friends go out to have fun. It’s a solitary life in many ways – but the more you’re willing to dedicate your life to your venture, the better your chances of making it.

Passion.  Great entrepreneurs really love what they’re doing and believe they have found their calling. (It’s this belief that makes the isolating factors of desire much more acceptable.)

In effect, work turns into play. Rather than dreading Monday morning, they can’t wait to get to work.

The best example of passion in an entrepreneur is Steve Jobs.  From the time he was a child, Steve’s passion was to build products that he felt could be revolutionary.

Indeed, when Steve was trying to convince John Scully, then the president of Pepsi-Cola, to head west and join Apple, he challenged Scully with the question, “Do you want to spend the rest of your life selling sugared water, or do you want to change the world?”

Even after he was fired from Apple, he steered two new companies to greatness: Pixar and Next.  Today, back at the helm of Apple, he accepts an annual salary of just $1 – because he loves what he does.

Of course, this combination of qualities does not guarantee success.  But if you possess all three and follow-through on the sacrifices they demand, you will certainly increase your chances.