Imagine you've agreed to give advice to a group of business students but you can't think of a theme. Here's a guaranteed winner: Go with "Follow your passions... and do what you love!"

That's advice everyone loves to hear. You'll kill.

You'll also be wrong.

"Telling someone to follow their passion--from an entrepreneur's point of view--is disastrous," says Cal Newport, Georgetown University professor and author of So Good They Can't Ignore You: Why Skills Trump Passion in the Search For Work You Love. "That advice has probably resulted in more failed businesses than all the recessions combined... because that's not how the vast majority of people end up owning successful businesses.

"Passion is not something you follow," he adds. "Passion is something that will follow you as you put in the hard work to become valuable to the world."

Here's why.

Career Passions Are Rare

It's easy to confuse a hobby or interest for a profound passion that will result in career and business fulfillment. The reality is, that type of preexisting passion is rarely valuable.

Don't believe me? Think about something you're passionate about. Or were passionate about when you were in high school. Write it down.

Then apply this test: Will people pay you for it? Will they pay you a lot for it?

"Money matters, at least in a relative sense," Newport says. "Money is a neutral indicator of value. Potential customers don't care about your passion. Potential customers care about giving up money."

A passion people won't pay you for is hardly the basis for a career. It's a hobby. You can still love your hobbies--just love them in your spare time.

The key as an entrepreneur is to identify a relevant passion.

Passion Takes Time

The "hobby" passion is much different from the kind of passion you hope to find in your business career.

"Producing something important, gaining respect for it, feeling a sense of control over your life, feeling a connection to other people--that gives people a real sense of passion," Newport says.

Roughly speaking, work can be broken down into a job, a career, or a calling. A job pays the bills; a career is a path towards increasingly better work; a calling is work that is an important part of your life and a vital part of your identity. (Clearly most people want their work to be a calling.)

According to research, what is the strongest predictor of a person seeing her work as a calling?

The number of years spent on the job. The more experience you have the more likely you are to love your work.

Why? The more experience you have the better your skills and the greater your satisfaction in having those skills. The more experience you have the more you can see how your work has benefited others. And you've had more time to develop strong professional and even personal relationships with some of your employees, vendors, and customers.

Where business success is concerned, passion is almost always the result of time and effort. It's not a prerequisite.

Passion Is a Side Effect of Mastery

The myth of the virtuoso is also a problem," Newport says. "In the majority of cases, people didn't think of someone who became a virtuoso as having unusual talent when they were very young."

Instead, most highly skilled people were exposed to something in a way that made it interesting. Take music: Something (a song, an instrument, a teacher, etc.) initially inspired them. They started learning and then benefited from what Newport describes as a feedback effect.

"If you practice hard, soon you might find you're the best in your group of students," he says. "That's great feedback and it motivates you to keep practicing. Then you're one of the best in a larger group and that's motivating too. Practice and achievement is a gradual, self-reinforcing process."

If the work is interesting and you think there's a market--meaning people will pay you for that work--that's enough to get started. Then the work itself will give you the feedback you need. Creating a viable product will motivate you to develop your skills so you can refine that product or create more products. Landing one customer will motivate you to develop more skills so you can land more customers.

The satisfaction of achieving one level of success spurs you on to gain the skills to reach the next level, and the next, and the next.

And one day you wake up feeling incredibly fulfilled.

"The satisfaction of improving is deeply satisfying, as eons of craftspeople will attest," Newport says. "The process of becoming really good at something valuable is a fulfilling and satisfying process in itself... and is the foundation for a great entrepreneurial career."

Working Right Trumps Finding the Right Work

Want to love what you do? Pick something interesting. Pick something financially viable--something people will pay you to do or provide.

Then work hard. Improve your skills, whether at managing, selling, creating, implementing--whatever skills your business requires. Use the satisfaction and fulfillment of small victories as motivation to keep working hard.

And as you build your company, stay focused on creating a business that will eventually provide you with a sense of respect, autonomy, and impact.

"Don't focus on the value your work offers you," Newport says. "That's the passion mindset. Instead focus on the value you produce through your work: how your actions are important, how you're good at what you do, and how you're connected to other people."

When you do, the passion will follow--and if you work hard enough, someday you'll be so good they can't ignore you.

Quick note: So Good They Can't Ignore You is the best book I read this year. If, after reading it, you aren't motivated and excited about working hard to become incredibly good at something... hey, there's no hope for you.