When I decided to start my own business, my two closest neighbors — both of whom worked for a huge corporation — were worried about my future, concerned about my losing the security of a paycheck. That was in January 1986.

Twenty years later, I'm still in business. Within two years of my starting a business, both neighbors had lost their jobs.

How the economy has changed in those two decades. Then, the best and brightest business school students hoped to work for Fortune 500 companies or mega consulting firms. When someone said "small business," they usually meant a "mom-and-pop" store.

Now a small business is just as likely to be a fast-growing innovative company.

Today, hundreds of universities and colleges offer degrees or certificates in entrepreneurship or small-business management. More than a half million new businesses are started each month, according to the Kauffman Foundation. And in a 2005 poll conducted by Junior Achievement, 69 percent of teens said they wanted to start their own businesses.

In 1986, almost no one used the word "entrepreneur." Now, everyone wants to be one.

What are the most important lessons I've learned about running a business during the past 20 years? What did I wish I knew when I was starting out?