7 Reasons Why Too Much Optimism Is Bad for Business As Nelson Mandela said, 'The brave man is not he who does not feel afraid, but he who conquers that fear.'

Becoming a successful entrepreneur requires a healthy degree of optimism. After all, you can't achieve big dreams without daring to dream big in the first place. And you can't take real risks unless you first believe in yourself. One of my favorite business-world optimists is Richard Branson. Branson had no reason to logically expect that he could use a music label to successfully fund the startup of an international airline and a mobile phone carrier, but he believed he could do it, anyway -- despite the unprecedented difficulty involved.

Related: Feel the Fear -- and Then Move Past It

As Winston Churchill once said, "Optimists see opportunities in every difficulty." No doubt Sir Richard agrees.

So, optimism is necessary in entrepreneurship. But it can sometimes blind us, as well. In my own experience, one of the most daunting difficulties optimistic entrepreneurs may contend with is simply coming to grips with reality. When life and business conspire to splash cold water in our faces, our optimism sometimes continues to urge us forward into bad bets, ill-advised decisions and certain failure. In other words, even optimism should have its limits.

Still, I have discovered a few governing realities that have helped me harness and bridle my optimism so that it can take me and my business where I want to go, instead of running wild. Facing those realities hasn't always been easy, but it's helped me achieve my goals.

1. You can't make everyone happy.

One of my heroes is Harvard Business School professor Michael Porter, whom some have called the "father of modern strategy." Porter went against the grain of conventional wisdom with this important truth: "All good strategies must make customers unhappy."

That might seem counterintuitive, but the simple fact is that it's impossible to make everyone happy. The best we can do is make a highly targeted group of people happy. And, luckily, that's enough.

So, pick your niche. Figure out what kind of customer you need, to succeed, and become good at making that person happy. When a customer comes through your business who doesn't fit your niche, be polite, but recognize that making him or her happy is not a part of your strategy. In other words, just let 'em go.

2. You can't do it all yourself.

There is a cap on the success control freaks can attain; hopefully you're not one of those. Instead, recognize that delegating is an important skill, because no matter how smart and talented you are, there simply aren't enough hours in the day to complete all the tasks involved in running a successful business.

Entrepreneurs with vision, meanwhile, may find it difficult to trust others with execution. I find that the secret is actually to duplicate, not delegate. Find and hire people who can actually duplicate the vision, energy and skill you bring to a project. It's the only way I myself feel comfortable handing over the reins.

Related: 8 Ways to Make Certain Optimism Doesn't Blind You to Signs You're Going Broke

3. There is no such thing as a 'work/life balance.'

For successful entrepreneurs, trying to achieve a work/life balance is a waste of time and energy. If we could be happy working 9-to-5 and then coming home to spend time with our families, we wouldn't be entrepreneurs! My solution has been to create a work/life blend.

Trying to adhere to a rigid schedule didn't work for me; the time commitments in my work life conflicted with the obligations in my personal life, and vice versa. The key, I found, was to stay flexible. By blending different combinations of both work and personal life into each and every day, I was able to meet all of the goals and obligations I laid out for myself.

4. There will be setbacks.

No matter how good you are, no matter how successful, you will suffer setbacks. Odds are, you'll be surprised by a down month from time to time. You will lose an important contract, or else a job you were counting on. These things happen to everyone, but they don't have to break your stride.

Something that media magnate Ariana Huffington once said that her mother told her has stuck with me: "Failure is not the opposite of success, but a stepping stone to success." Failure teaches us important lessons we can't learn any other way. Failure strengthens us, and every setback prepares us for the next success.

5. You have to know when to walk away.

When they first start out, many entrepreneurs believe that the key to success is never quitting. Nope! There are many times when quitting is completely appropriate and necessary, and it's important to recognize them.

Kenny Rogers laid out a pretty good entrepreneurial strategy in The Gambler: "You got to know when to hold 'em and know when to fold 'em. Know when to walk away, and know when to run!" Shark Tank star Kevin O'Leary says that if you aren't making a profit after 36 months, you don't have a business . . . you've got a hobby. If you're investing all your time, money and energy into a hobby, it's time to walk away. (Or maybe run!)

6. Business success is not personal success.

For many entrepreneurs -- myself included -- it can be hard to draw the line between the personal and professional. But the world of business is a ruthless game of numbers; you can't invest all of your happiness and self-worth into the success of your business. I learned that the hard way when I tattooed the logo of my first business venture onto my body. I threw my entire being into the success of that business, and when it crumbled, I nearly did, too.

What I learned was that succeeding in business is very different from succeeding as a human being. To succeed in business, you often have to take all of your hopes, dreams and fears out of your decision-making process and do what the numbers tell you to do. That is not a recipe for winning friends and building a family, but it is necessary to make wise business decisions. Invest your deepest feelings in people you love, not in your work.

7. Maintain a healthy dose of fear.

Entrepreneurs are typically thought of as fearless, and for good reason. But fear is good for entrepreneurs. Fear of failing and fear of letting others down keeps us sharp. It keeps us from rushing into less-than-ideal opportunities. Fear forces us to do our due diligence and weigh our options.

The trick is to let fear guide you without paralyzing you. Because, and I hate to break it to you, being an entrepreneur is scary. As the person in charge with so much at stake, you are going to feel fear. Often. So, use it! Fear can be inspirational.

Related: Don't Fear the Fear -- Let It Drive You

As Nelson Mandela said, "The brave man is not he who does not feel afraid, but he who conquers that fear." That, my friends, sounds like the definition of success.