The old joke begins with a question: "When did you first decide to become an entrepreneur?"

"Well," goes the reply, "I decided right after my boss said those two little words: 'You're fired!"'

It's a good joke, but it begs an even better question: Why do entrepreneurs become entrepreneurs? And perhaps more importantly to the aspiring entrepreneur: Why do you want to become an entrepreneur? The answer to that question likely will be significant in answering yet another one: Will you succeed as an entrepreneur?

People decide to start their own businesses for a multitude of reasons. Perhaps the three most often mentioned are necessity (I'm not making enough money), money (as in I want more of it) and self-determination (I want to live life on my terms). Other motivators might include a passion for a specific product or idea, hunger for personal prestige or power, a love of risk or a desire to "win the game."

Most successful entrepreneurs focus on developing a profitable operation, but I think the best entrepreneurs are driven by something even more compelling than a nice paycheck. They want to invest themselves in something that will change the world in greater or lesser ways. This might sound like a high standard, but most often a game-changing product or service is NOT required to qualify. Instead, the entrepreneur's passion might revolve around something as simple as the idea of creating a better workplace, solving a nagging but not life-threatening problem or marketing an existing product in a new and innovative way. The key here is that the entrepreneur is focused on the IDEA, not just the money.

For example, a local entrepreneur founded a company that is marketing a previously known but recently unavailable anti-bacterial product that is just as effective and much longer-lasting than the more commonly used alcohol-based products. He launched the

Fred Smith, the founder of FedEx, prepared a term paper for his college economics class that laid out the basic ideas of his first-of-its-kind company six years before it was actually launched. Even though the project faced daunting obstacles (including the capital cost of securing 14 jets before operations could begin), he was sufficiently passionate about his idea that he put up his entire $4 million personal and family fortune to make it happen. The first night the company shipped only 182 packages on those 14 jets.

Even Donald Trump, who last year was voted the world's most competitive businessperson, said that he wanted to be remembered as "a builder who has enhanced the cities and communities where I have built and/or developed." He also said: "You have to love what you do. Without passion, great success is hard to come by. An entrepreneur will have tough times if he or she isn't passionate about what they're doing. People who love what they're doing don't give up. It's never even a consideration. It's a pretty simple formula."

With most great entrepreneurs wealth creation is an important and expected result of their labors, but it is rarely the primary motivation. In fact, money is often a poor motivator for an entrepreneur because it rarely comes quickly and often only after months (or years) of struggle, doubt and uncertainty. The larger passion provides the entrepreneur with the power to keep going when the results are uncertain.

So why do you want to become an entrepreneur? If it is only because you heard those dreaded two words from your boss, you might want to reconsider. If, on the other hand, you think you can change the world - whatever that means to you - entrepreneurship is a wonderful way for you to make a difference and a profit at the same time.