The most important quality for success in entrepreneurship and in life is the quality of optimism. Optimists have an unrealistic expectation of success.

As a result, they are willing to try far more things without becoming discouraged.

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In addition, because of their unrealistically positive attitude, they are willing to persist much longer than the average person. Optimism is a wonderful quality as long as you have it under control.

In order to be successful in business, and in any activity where your money is involved, you must temper your optimism with negativism. You must be enthusiastic about the possible upside of the investment but you must be skeptical, critical, suspicious and demanding about all the different ways that your money can be lost.

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Seek out and listen carefully to people who are negative toward your idea. Look for negative thinkers, because their viewpoints can be invaluable and save you a fortune in time and money. I have a friend who is a lawyer and gives advice to many people on investments. And he does something very unique.

When clients want to make an investment that they're unsure about, he asks them come to his office and sit behind his desk. And then he presents the investment to them and asks them to critique the investment as though they were he.

And he says that when his clients begin critiquing the investments they're thinking about going into, when they begin becoming negative thinkers about the investments, he says they are astonished at how bad the investments really are.

He said he has saved his clients millions of dollars by forcing them to be negative thinkers about their own ideas, simply by switching roles and sitting in front of the desk while they sit behind the desk.

But don't be overly influenced by negative thinkers. Just take their viewpoints into consideration. There's a famous story of Mary Hudson, who started off with $200 in the middle of the Depression and leased a gas station that two men had gone broke running at two different occasions.

And from that she built a company called Hudson Oil, which is now the biggest independent distributor of gas and oil in the United States. From a $200 investment, even though everybody told her she would fail. So remember, listen to negative thinkers, but don't necessarily accept their advice.

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Here are two things you can do immediately to get these ideas into action.

First, view your idea as if you were an outside consultant. Ask, "What are all of the possible risks or flaws in this cause of action?"

Second, seek out the opinions of others. Listen without responding or defending. Thank them for their input. They may save you a lot of money.