In the enthusiasm of the moment, going into business for yourself sounds great. Too many people do just that. They open their doors without ever planning where they want the business to be in a few years. Most of them fail.

Entrepreneurs who make their businesses last through eventual retirement are the analytical, careful types who have always set long-term goals—and more importantly, have the discipline to keep them.

“You’ve got to have a goal,” points out trainer and consultant Jeffrey Mayer, president of www.SucceedingInBusiness.com. “If you don’t know what the goal looks like, how do you know when you are successful?”

That doesn’t mean the objective can’t be changed when it’s no longer useful. Your own needs may change. The business may grow in a direction you didn’t foresee. Or if you’re fortunate, your business could surpass the original goal.

A goal is the lodestar that guides you when you question yourself, that keeps you from diverting energy into pointless blind alleys. It maintains your focus on what’s really important to your business and its growth. It’s not sacrosanct in itself.

“Tinkering with a goal is fine,” Mayer says. “Look at the results you’re getting, and how you can modify it. You don’t need perfection the first time.”

Keeping to a valid goal when short-term concerns threaten to overwhelm the business takes determination, and lots of it, for entrepreneurs are sure to be tested many times.

And it’s not just in setting goals that entrepreneurs need determination. To really succeed, entrepreneurs need to be determined every time they walk in the door.

With determination, you’ll learn what you don’t know now, find creative solutions to that vexing problem, and work smarter to beat the guy down the block.

Not that determination makes everything easy. As entrepreneurs find out soon enough, owning a business is for the resolute.