This article has been cross posted with Business Week.

Entrepreneurship has become faddish of late, and business school students are not immune to the fervor. I have devoted more than 30 years to the study and practice of, and investment in, entrepreneurship, and here’s my advice: take a gimlet-eyed look at what the entrepreneurial life entails before you take the leap.

Entrepreneurship is almost never about working in flip-flops in an incubator; it is tough work that requires extraordinary effort. It is super full-time and super risky. In today’s tough job market, “doing a startup” may sound better than “unemployed,” “getting my third master’s degree,” or “staying with my folks awhile.” But entrepreneurship is for those who are laser-focused on building a company that will scale; it is a marathon, not a sprint, usually requiring a decade or longer of commitment.

Students, like the rest of us, should be prepared to separate myth from reality. Like most fads, entrepreneurship has its own mythology. Here are some of my favorite examples:

Having a startup makes you an entrepreneur. Saying that starting a new venture automatically makes you an entrepreneur is a little like saying that if you put on skates and grab a stick, you’re a hockey player. The vast majority of startups are founded by people who do not see themselves creating a new market or who lack the managerial skill to go the distance. It is not a coincidence that the Kauffman Foundation coined the phrase jobless entrepreneurship, words I would recommend putting as a warning label on every startup idea.

Entrepreneurship is for the young. Not only are many valuable ventures started by people 40 and up, there is reason to believe that industry knowledge, wisdom, managerial experience and a rich contact list can help get a venture off the ground faster and with better backing. Even if launched by a student, grey-haired mentors, investors and partners are almost always required to get into the marketplace and the stamina to stay there. Primesense, a maker of 3D sensors reportedly bought by Apple (AAPL) for $350 million, was founded by thirty-somethings, but they were closely coached by Dr. Orna Berry, a prominent tech executive and venture capitalist who is over 60 with 30 years industry experience.

Entrepreneurship requires passion. If by “passion” you mean energy, commitment, hard work, and self-confidence, well, yes, of course. But passion can make you blind.  An entrepreneur who is going to conquer or create a market must have the ability to face facts without blinders, and course-correct or drop out when those facts force reconsideration. When Microsoft (MSFT) stopped using Primesense technology in the Xbox 360, the startup made the dispassionate (and painful) decision to slash payroll in half and shift its strategy to focus on smaller, less expensive devices.

Entrepreneurship requires innovation. The vast majority of successful ventures are based more on amazing execution than invention or innovation. Many are even outright copycats, pasting a proven business from one side of the globe to the other. Others are minor tweaks of an established winner. To be sure, there are many examples where new technologies, inventive business models and novel processes have been a key component of an entrepreneurial venture. Even in those cases, amazing execution is a sine qua non of growth and success. But often value is unlocked with an incremental twist on a tempered template (something I have called “minnovation”) coupled with relentless speed and skillful leadership.

My students (and my research as far back as the Phoenicians) helped me realize that entrepreneurship is an integral part of being human. It has the potential to contribute to personal wealth and self-actualization. That is not to say that everyone should or can be an entrepreneur, just as not everyone is an artist or musician. But like art and music, entrepreneurship has existed for millennia and is part of the human experience.

So as you are weighing your post-business-school career options, question the simplistic assumptions about entrepreneurship. If you still think the entrepreneurial choice is for you, do it with eyes wide open.