I believe that bruises, not books, are the best teachers and that calluses, not cum laudes, are the best evidence of higher learning. In America's winner culture today, we spend too much time celebrating our victories and not enough time respecting the lessons we learn from our failures.

One of the side benefits of writing columns for Forbes is the hundreds of letters and emails I receive from readers every month. A significant number of them say they want my job: giving speeches, making investments, traveling to cool places, talking with smart people, buying and growing companies, and advising corporations. Hey, come to think of it, this is a great job. Mostly, people want to know where to go to school, or what to study, and what they have to do to be successful.

I always write back the same thing. Do something you love, learn something new every day, find the smartest, most decent people you can and stay close to them, be someone other people can count on, and don't be afraid to take risks--don't be afraid to fail. In my career, mistakes are where I learned the most --I wouldn't trade them for anything in the world.

In our family the motto was "never give up." The family heroes were Grandpa Bill, who walked to work at the asbestos factory, Grandma Flora, who built a barn with her own hands when she was 60 years old, and Uncle John, who told stories about riding the railcars during the Great Depression looking for work. But my biggest hero was my dad, who worked for a dozen companies before he found steady work, who went to work every day before dawn when I woke up, who was the guy everyone in town came to when they needed help--and whom I never once heard complain. I was taught it was not a sin to be thrown from a horse, but it was a sin to stay on the ground. But the worst sin of all was not to try in the first place.

A good thing, too, because most of what I know has come from the bumps and bruises acquired while trying to do things I didn't know how to do. It's not exaggerating to say that the reason I have owned my own business and worked for myself for the past 20 years is because, with my résumé, I'm the only one willing to hire me.

For example, there was the day I learned about being careful. Sixteen years old, wearing my new Pepsi work shirt, I thought I was pretty cool. I was sitting in the helper's (shotgun) seat of a huge Pepsi truck, looking out at the large rectangular rearview mirror that stuck out on the right side of the truck. The route driver gunned the engine to make a left-hand turn onto a busy Chicago highway, trying to make it before the light turned red. As we turned, a wall of Pepsi, nearly 500 cases in all, blotted out the sun in the rearview mirror. The complete contents of one side of the truck were thrown out onto the busy highway. The driver's helper--that would be me--had forgotten to close the side doors and secure the load at our last stop.

For two hours I picked up broken Pepsi bottles with a broom and a piece of cardboard as the driver, personally responsible for the value of his own breakage, repeatedly clenched and unclenched his fists by the side of the road. Thus ended my short but colorful career at Pepsi. I learned two things that day: I was not cut out for jobs that required paying attention, and centrifugal force was something not to be ignored.

Another time I needed a new amplifier for my guitar (in high school, being in a rock-and-roll band was the only guaranteed method to get girls), so I decided to seek further employment, this time as a short-order cook in a drive-in restaurant. No problem, the boss said. When the carhops brought in a new order, they clipped it onto a revolving wheel so I could turn it around to read the order. He didn't know I was so nearsighted (20/400) I couldn't see the wheel at all, much less the orders. I kept this condition secret from everyone. (In 1962, glasses were definitely not cool.) By the end of the first night, I was washing root beer mugs, my exclusive assignment, while the boss cooked all the food himself. There was no second night. The morals here: Don't sign up for something unless you can deliver it, and vanity is a dangerous thing.

Halfway through high school I thought, "This is boring, I'm going to go to college--now." Surprisingly, I was admitted and entered college, where I joined a fraternity. During my first year I applied myself with diligence to the three Bs: babes, billiards, and bourbon. I did less well in attending class and other academic areas. After an undistinguished freshman year the dean and I agreed I would go and find myself--in some other state--until I learned how to deliver on commitments. This naturally brings me to my next career.

At a paint factory I earned $62 per week and got to wear a white lab coat (not as good as a Pepsi shirt but still pretty good for getting girls) as a quality-control technician. My job was testing every batch of paint for color, hardness, and viscosity. Well, almost every batch. It seems I missed testing a 1,500-gallon vat one day, which an industrial customer later used to paint an entire factory. When the paint dried it literally fell off the walls--it seems the entire batch had been mixed without any resin, the stuff that binds the pigment to the paint. After a brief conversation with my boss, I reapplied to school.

Armed with recent evidence that I was not well suited to earn a living in the real world, I decided to become a college professor. This time I applied myself with a vengeance, even copying my textbooks by hand to memorize them. I studied, I showed up, I turned in term papers on time. Such work helped me earn my bachelor's degree and a place in graduate school where I completed my Ph. D. in economics in less than three years. I had finally learned the work habits that I have used ever since to build my career as an economist, business and investment advisor, and private equity investor. Each misstep along the way helped me to learn how to work, how to handle myself, how to be a partner.

Scared off by the crash, investors lost their appetite for the market, and it became very difficult to grow the assets of the fund. With our breakeven point looking unreachable, we examined our alternatives. We could raise more capital and risk losing even more money for our investors. We could sell the fund to a larger fund, which didn't seem right, since investors had come to our fund specifically to invest with us. Or we could simply close the fund down and send our shareholders their money back, and our venture capital investors what was left of theirs. We chose the latter course and wound down operations.

Looking back, I think we threw in the towel too early. If we had had the tenacity to hunker down a little longer, and the faith that the market would rebound, we would have made it. But I still learned some valuable lessons: I learned to lose money in the market without losing faith. And I learned not to start a venture without sufficient capital to see it through to completion.

Today, my partners and I manage a fund in which we buy and grow many different types of businesses. These lessons, and hundreds more like them, are the real assets of our business. Falling off a horse, and getting back on again, is the only way I know how to learn them.