NEW YORK (CNN/Money) - Marian Grant began her career at Procter & Gamble and seemed destined to stay with the company until retirement. But in 1998, after 20 years with the company, the former advertising executive for Cover Girl cosmetics bid adieu to corporate America and enrolled in nursing school.

"I liked my job, but at the end of the day I had a vision of standing at the Pearly Gates saying, 'Hey, I helped bring the world a better lipstick,'" said Grant, who at age 46 is now an emergency care nurse at Johns Hopkins hospital and studying to be a nurse practitioner.

Making a radical career change is not for the faint of heart. Those who dare to start over risk rejection, frustration and regret, not to mention a smaller paycheck. Yet, if you've climbed half way up the proverbial ladder only to discover that it's in the wrong location, jumping off may be the best thing you can do.

Grant, for one, began thinking about a new career in the mid-1990s because she feared she might be downsized. The layoff never happened, but Grant realized that she found more satisfaction in volunteering at an AIDS hospice than she did promoting new cosmetic lines. "It took a while to get my head wrapped around the idea of going back to school," said Grant, who thought about the move for four years before taking the plunge.

It's tough to track down how many professionals actually make a mid-life career change.

The Bureau of Labor Statistics reports the average person holds about 9 jobs between ages 18 and 34. That doesn't indicate whether those surveyed, however, simply found a new job in the same line of work or changed their careers entirely.

A clearer picture of how often career changes cross the minds of working adults can be drawn from a 1998 Gallup survey, sponsored by Inc. magazine. When asked if they were just starting out and could choose their life's work all over again, 47 percent of those surveyed said they'd try something new. Fifty percent said they'd remain in their current field, while 3 percent said they didn't know what they would do.

If you're thinking of following in Grant's footsteps, you'll have to give it careful consideration.

"You must have a plan," said Susan Battley, an economic historian turned clinical psychologist, turned career coach. "Those who flounder are those who leap before they look."

Most of the people Carol McClelland counsels come to her with no clue about what they want to do. "My job is to ask as many questions as I can to try to shine a light on the answer," said McClelland, a specialist in life transitions and author of "Changing Careers for Dummies." Some of her former clients included a sales manager who is now an ordained minister and an accounting employee who is studying archeology.

McClelland recommends you start by thinking in ideal terms about what you want out of a job and the lifestyle that comes with it. There are dozens of factors to consider, such as what subjects interest you most, what processes you enjoy (e.g., do you want to spend your day talking to people or building things), what kind of hours you want to work, how much you need to earn, and what office culture, if any, suits you. "For some people, work environment is far more important than what they actually do," she said.

Of course, you'd be hard-pressed to find a job that fits every ideal. A high-income job, for example, may not come with nine-to-five hours and a casual dress code. You need to prioritize and revisit that list of priorities as you consider different job prospects.

It's one thing to think you've found you're dream job, quite another to understand what that job actually entails.

"If you're on Wall Street and want to become a rancher, I hope you're prepared for what that means," said Paul Ray Jr., CEO of the executive search firm Ray & Berndtson. "You can't just have a great idea. You need to do a great deal of research."

Get an inside look at a profession by volunteering on site, talking to others in the field, logging on to industry chat boards or going to conferences. Find out whether your experience alone could get you in the door or whether the job requires you to go back to school. "Schooling makes sense when it's very directed," said Ray. "A nursing student can rest assured that there is plenty of demand, but for someone who decides to get an MBA there may not be a job when they graduate."

At the same time you get to know the pros and cons of the job, you'll want to learn about the industry as a whole. Find out whether it's growing and where the best job opportunities are. "You need to understand the new industry. Not just what kind of business it is, but also how it operates, how it evolves," said Ray.

Once you've identified your dream job and researched it, you'll next need to convince a would-be employer or customer that you're qualified for the job.

"A few years ago it was much easier. Companies were desperate to hire and they were thinking outside the box," said Harvey Bass, CEO of Stascom Technologies, a recruiting firm that specializes in information technology and medical equipment. "Now they're looking for the perfect fit. They're not going to consider someone with no experience in their industry."

Discouraging words. But before you give up completely, keep in mind that every industry is different. Certain fields are more open to outsiders than others, particularly if, like nursing and teaching, there is strong demand.

Moreover, not every employer is looking for people with exactly the same experience. "There are so many life experiences that are transferable," said Emily Viner, director of financial representative recruiting for the Guardian Life Insurance Co., which trains outsiders. Last year's agent of the year, for example, was a former engineer. "If I see someone who's been successful in a field, has good interpersonal skills and is articulate, I'll consider them. Anyone can learn the mechanics of a product," said Viner.

Even if you're convinced that your new career is going to be better for your bank account, you'll feel better about the transition if you get your finances in order before you hand in a letter of resignation.

When Grant thought about leaving her executive post to go to nursing school, for example, she knew that she'd not only be in school but that she'd be taking a substantial pay cut when she started work again. Before she made the move, she and her husband examined their finances, cut their expenses, and refinanced their mortgage.

Grant also considered how changing careers would affect her retirement. Fortunately, she diligently contributed to her retirement fund while at Procter & Gamble. What's more, she realized she would stay in nursing far longer than she would have stayed in the corporate world. "This is a job I could see myself doing in my 60s or 70s," she said.