Starting over can mean forgoing a regular paycheck.

The primary risk many professionals face hen they change careers or venture out start a business is loss of a large paycheck.

And few know that better than David Steinberg, whose annual pay went from "over $100,000 to zero - the ultimate pay cut" when he left his job as vice president of business and legal affairs at Miramax Films last July to start work on his own.

Only 33, Steinberg concluded that "life is too short" and realized he was ready to leave behind the politics of corporate life. But politics was not all he left behind - he also lost the security of a regular paycheck.

"I have nightmares and wake up wondering if I'm going to be able to make my mortgage payments," said Steinberg, who now earns his living by handling legal work on film production and distribution for intermediate-size film companies. He does all this from his Hollywood Hills home - a home for which, he is happy to say, the bank still receives his monthly mortgage payments.

Bob Safai, a 35-year-old real estate broken also decided to leave behind a long stretch of working for large employers and strike out on his own.

Safai left his job at Beitler Commercial Realty Services after seven years to start Madison Partners six months ago. He said the biggest risk is that of having only yourself to look to for income.

"A broker can go many months without making income," said Safai. "You're taking a risk by banking on yourself. You're the entrepreneur (and must compete with) the large institutions. I'm competing with brokers at companies with recognizable names."

So far, Safai's decision has paid off. Madison Partners has sold more than $100 million worth of properties since its inception, and now employs four brokers.

In going out on their own, both Safai and Steinberg learned that even mundane endeavors can pose a significant risk to an entrepreneur. For example, administrative issues weighed heavily on their efforts to start up a business.

"Paper work and getting a computer system going was such a hassle," said Steinberg. "A lot of it I muddled through."

Leaving behind a career in which you've devoted a significant amount of time and acquired all of your job skills can be as harrowing as setting out on your own.

"I threw away the reputation I had developed at the company and all the skills I had," said Matt Holzman, who had been a computer systems consultant and is now in charge of obtaining corporate and foundation donations for Santa Monica-based public radio station KCRW.

Holzman had graduated college with a degree in computer science and designed manufacturing information systems for Arthur Andersen LLP. But within two years, Holzman - and those around him - realized that he had chosen the wrong career.

"One day my boss said, 'You don't seem very happy'," said Holzman. "I thought, 'She's right,' and I quit."

After trying his hand at being an information systems headhunter for about a year, and a stint as a bartender. Holzman began to volunteer at KCRW. Management eventually recognized his skills at convincing companies to donate gifts or services for subscribers, and be was offered a permanent position.

Despite the way his decisions have played out, 33-year-old Holzman said that today he might exercise more caution before making a change. "Last time, the decision was made on my gut. Now a similar decision would be difficult to make," he said.

Chris Oliver also knows what it's like to leave behind the comfort of a job and a city he knew well - to risk the possibility that he would not like his new job or his new home.

Oliver had been based in L.A. designing rides for Walt Disney Co.'s Florida parks. Despite the glamour of this job, Oliver grew weary of 90-hour work weeks and the congestion of L.A. He decided to move to Atlanta to be closer to his family and took a newly created job at Coca-Cola Co., heading up a department responsible for vending machines.

"You don't realize how far into a comfort zone you are until you actually leave it," said Oliver. "What really scared me was going into an unknown area in a completely new department."

Carole Black ignored everyone's advice when they told her not to leave her job as senior vice president of marketing for television at Disney.

"I had many people tell me that I should never leave a highly paid position without choosing my next opportunity, and that I was being very foolish," said Black.

But Black quit her job to travel around the world and decide what she wanted to do next.

Black had several job offers and, during a month-long stay in Italy, she chose an offer to become general manager of KNBC-TV Channel 4.

At 51, Black does not regret the risks she has taken and now offers her own advice about overcoming the fear of taking a risk. "The only security anyone has is one's own self," she said.