Robert Herjavec knows what it's like to build from the ground up. Born in Croatia, he and his family immigrated to Canada when he was a young boy, with little money or grasp of English.

Always ambitious, he persevered; working as a waiter and selling computer parts among other odd jobs, until he launched his first company, BRAK Systems, from his basement in the early 90s -- and sold it to AT&T 10 years later for $100 million.

He is currently the founder and CEO of the Herjavec Group, a 12-year-old global company specializing in cyber security. Herjavec is also an investor and a leading shark on ABC's Shark Tank, which just wrapped its sixth season. He also happens to be a bestselling author, races cars in the Ferrari Challenge North America Series and competed on season 20 of Dancing with the Stars.

We caught up with Herjavec to talk about not letting fear paralyze you, making sure you go into business for the right reasons, and what entrepreneurs can do to prep for a big pitch meeting.

Q: Knowing what you know now, what would you have done differently when you were first starting out?
A:
I would have believed that the sun always rises tomorrow. I think I had a certain level of anxiety about getting things done in the moment, which is good, but I would have had a longer-term view.

Related: Shark Tank Star Robert Herjavec on the 5 Worst Sales Sins

Q: How do you cope with that anxiety?
A:
One thing is experience. I think when you get old like me, you realize the sun really does rise the next day. I think the other thing is fear. If you let your fear dictate how you feel about others or things that are going on, it can paralyze you.

Q: How can young entrepreneurs benefit from this knowledge in their lives?
A:
If you want to build a business, do it for the right reasons and to build something great. And if you happen to sell it along the way to Google for a billion dollars, that's okay, too.

Q: What are you glad you didn’t know then that you know now?
A:
I think the other thing you do when you get to my age is you realize that things can go really bad. I had no fear when I was younger. I had no responsibility. You know, there's a reason why it's good to start a business when you're younger, because you don't have as much to lose. That adage is really true. Sometimes when you love something so much and afraid you're going to lose it you tend to get a little freaked out.

Related: Shark Tank Star Robert Herjavec's Top 10 Tips for Entrepreneurs

Q: You've heard countless pitches on Shark Tank. What makes a pitch stand out to you? What should entrepreneurs do to prepare?
A:
The first thing we look for is someone who can grab our attention. We sit there 12 hours a day, 17 days in a row. We get bored and hungry and antsy. You've got to grab our attention. My best advice after being on Dancing with the Stars and having to learn how to pitch myself every week is learn your business and your numbers so well that you can just forget it. And then go out and sell the dance.

[Dance] like business, is a competitive sport. Typically in any business for you to win, someone has to lose. There are very few businesses that are a net sum game. So that level of competition never goes away. When you're small, you love it because you're competing against really big companies. But when you’re big you tend to gravitate towards stability. As Mark Cuban said to me a long time ago, every day somebody wakes up with the sole intention of kicking your ass.

Q: What's your best advice for someone who is starting their own business?
A:
Love what you do. Do it for a reason greater than yourself because if you're passionate about it, and you're doing it for the right reasons, even if it doesn’t work out, you're going to be happy to go to work every day. It's hard to get to great unless you start at happy.

Related: Want to Go on Shark Tank? Here's What You Need to Know.