What Makes a Successful Entrepreneur? Perseverance. Entrepreneurship is about being the last man standing. It's about having the determination, the discipline, and the cash to see it through.

Entrepreneurship is not the glamorous career path it's been made out to be. It's not about big ideas and ideals. It's not about hopes and dreams. It's not about guts and glory. It's not even about invention and innovation. And it's certainly not about a search for fame and fortune.

More than anything, entrepreneurship is a game of attrition. It's about having the determination, the discipline, and the cash to see it through. It's about not giving up and being the last man or woman standing when everyone else has fallen by the wayside.

Don't get me wrong. Having the vision to see what others don't, the passion to motivate yourself and others, the savvy to build and grow a business, and the guts to make good decisions, are all part of the mix. But what binds those ingredients together is the tenacity to stick with it, day in, day out, year after year.

Make no mistake, successful companies have no endpoint. That's right, they don't. The goal is to keep overcoming obstacles, growing sales, and making money, ad infinitum. If reading that sends a cold chill down your spine, you're not alone. The prospect of having to keep all those balls up in the air and grow a business indefinitely is daunting to most.

Related: Learn to Write, for God's Sake

The few that find the notion intoxicating to the point where they can't wait to get up every morning, get to work, and deal with the chaos of their chosen path in life are the true entrepreneurs of the world. Here are a few real examples to drive home the importance of perseverance in startup success:

Nobody got Google at first

I bet you didn't know that Larry Page and Sergey Brin pitched their idea for a standalone search-engine company all over Silicon Valley before Sun co-founder Andy Bechtolsheim finally wrote them a check for $100,000. And in 1999, Google was ranked seventh with just 7.8 percent of the search-engine market. It took years before the startup hit critical mass, came to dominate the market, and became a popular verb all over the world.

Jeff Bezos' "purposeful Darwinism"

Jeff Bezos may have gotten a jump on ecommerce when he founded Amazon in 1994, but it wasn't some grand vision that enabled the Seattle-based company to survive the nuclear fallout of the dot-com era and thrive through the Great Recession. It was the tenacity of a highly competitive, results-driven culture built on a version of survival of the fittest Bezos calls "purposeful Darwinism."

Jobs: Perseverance distinguishes successful entrepreneurs

In a 1995 interview, Steve Jobs said, "I'm convinced that about half of what separates the successful entrepreneurs from the non-successful ones is pure perseverance. It is so hard and you pour so much of your life into this thing, there are such rough moments in time that most people give up. And I don't blame them, it's really tough." Indeed, Apple has persevered; the company was nearly bankrupt when Jobs returned as CEO in 1997.

Interestingly enough, Apple has only played a role in creating one market, the personal computer. MP3 players, smartphones, and tablets had all been around for many years when the tech giant entered those markets with a superior product painstakingly designed with the highest standards in mind. The Cupertino company as always taken the long view – and taken its time to be the best at what it does.

Related: Want to Save the World? First Save Yourself.

VC: One of the things I admire most is tenacity

In a recent blog post appropriately titled "Tenacity," VC Fred Wilson said that's one of the qualities he admires most in leaders. "Every successful company I have been involved in has gone through periods where things didn't work, where something important took too long and the doubts start to creep in," he said. "Employees start to lose faith, the media turns cruel, and you've got to hold it all together."

Wilson should know. His firm's notable investments include Twitter, Zynga, Etsy, Tumblr, Feedburner, and Foursquare, several of which have come under harsh scrutiny as public companies.

He also said it took years for SoundCloud to ink licensing deals with the music industry. And although Foursquare recently announced a down round of funding and that its founder, Dennis Crowley, would be stepping down as CEO, Wilson said the location awareness company has "survived and thrived" due to its and Crowley's tenacity.

Lastly, Wilson said, "It gets harder, not easier, as the years pile up. That is where tenacity and believing in yourself and your team and your business is required."

Indeed. Just as with life, successful businesses are marathons, not sprints, except there is no finish line. It's just a way of life, so live it up.

Related: Want Big Things Out of Life? Expect Big Things of Yourself.