Starting a successful business is a dream for many people, as proven by the popularity of ABC's Shark Tank. The hit show can teach us many great lessons about entrepreneurship. When TJ Hale, author of the Ultimate Guide to Getting on Shark Tank and I asked former Shark Tank contestants to share their biggest lessons, they generously agreed and candidly shared these 15 valuable business lessons learned from bravely putting their businesses in front of "the sharks."

1. Validation Matters

Having successful entrepreneurs validate your idea, whether they invest or not, gives you a great level of confidence to know whether to move forward or, as the sharks say, "put it out of it's misery."

"Getting an investment from a shark is pretty much the equivalent of Michael Jordan saying 'Hey, Nice Fade-Away jumper.'" -- Michael Szymczak, OrigAudio

2. Believe in yourself

Other people, maybe even the sharks, will tell you your business sucks. They probably have good reasons for that. But you have to trust your gut. If you know something is right, go for it, no matter what anyone says.

"I'll never be able to answer 'why' things didn't turn out the way I envisioned it, but I'm not going to dwell on it and let those thoughts get in the way of success." -- Julie Busha, Slawsa

3. Be Prepared

Be able to answer any question the sharks throw at you. Know everything. Know every detail about your business, numbers, customers, industry, inventory, etc.

"I read every book the sharks had written. I watched every single episode of Shark Tank. I practiced my pitch over 1,000 times." -- Jason Hanson, Spy Escape

4. When opportunity comes along, you can still blow it

Opportunity is just opportunity, you still have to execute. Once you get an investment, you still have to do the work, meet the commitments and get the results.

5. Be yourself

Don't fake it. The sharks are good at spotting phonies. Even though it can be hard in stressful situations, be your authentic self.

6. You're selling yourself, not your product

You are selling yourself more than you're selling the business. The sharks know the business can be changed and adapted, but if they invest, they are stuck with you.

7. Know who you are talking to

Everyone has their own point of view, history, expertise and preferences. When you pitch, know as much of that as possible.

"It's important to hit on the points of your business that appeal to any individual investor, making the business interesting and relevant." -- John Tabis, The Bouqs

8. Keep your sense of humor

Entrepreneurship is a high-stress activity and it will get tough. A good sense of humor will help you through those tough times.

9. Be patient

It takes time to get from the show's application to preparation to a deal. Patience are an important part of starting a business and you better have lots of them.

10. Don't expect a lifeline

Your business has to have merit and stand on it's own without an investment from a shark. They will not invest in a company that needs "rescuing." The merit and value must be there to begin with.

"Don't count on Shark Tank to save your company, count on Shark Tank to enhance your company." -- Ari Hoffman, AngelLift

11. Be ready for volume

When your product is exposed to 7.9 million viewers, no matter what the sharks say, you will get customers. Be ready to handle massive volume.

12. Take risks

Nobody achieves success without taking risks. Playing it safe is not how you create a successful business.

"It was not easy to go on national television and talk about all the issues I'd had in starting my business, but the risk paid off." -- Jayla Siciliano, Bon Affair

13. Be tough

You might get eaten alive by the sharks. Just ask Lori Cheek. You have to either believe in yourself enough to move forward anyway or go back to the drawing board.

14. Don't be attached to an outcome

The exact thing you expect to happen may or may not happen. Don't be attached to it. Something even better may happen.

"We thought Lori Greiner would be very interested but she dropped out. You have to roll with the punches. The experience and outcome has been better than we could have ever imagined!" -- Rick Hinnant, Grace and Lace

15. Do it now

Don't wait. If you have an idea you want to take to the world, do it now. The biggest regret most entrepreneurs have is not starting earlier.

PHOTO GALLERY 'Shark Tank' Contestants Reveal Their Biggest Lessons Learned