8 successful entrepreneurs reveal the best business advice they ever got

It's not just moguls like Daymond John who discuss the importance of gratitude. Science says it boosts your chances of success. Adam Jeffery|CNBC

Even today's business gurus had to start somewhere — and building a company from the ground up often involves taking advice from people you trust.

To tap into this wisdom, CNBC asked a handful of successful entrepreneurs and members of the YPO chief executive network about the best business advice they ever received and who gave it to them.

Here's what they had to say:

1. Marcus Lemonis, entrepreneur and star of 'The Profit'

Best advice: Keep your word and do what you say you'll do.

"The best advice that I was ever given was about shaking hands and making a deal. Oftentimes, people think that the only way to make a deal is to sign a legal document — but if people want to get out of the legal document, they're going to get out of it.

"It sounds odd, but my mother gave me that advice. She said, when you shake someone's hand, you have to honor the deal that you made and you have to do what you say you're going to do. If you made a bad deal, shame on you but that's the deal you made, so you're done.

"Actually agreeing to something with somebody has to mean something. On the show, 'The Profit,' all of my deals are initially done with a handshake. Ultimately, I do paperwork, but if you want to know what the movie’s going to be like, watch the preview — and that’s what the handshake looks like to me.”

2. Daymond John, founder of FUBU and ‘Shark Tank’ investor

Best advice: You can never save too much money.

“The best advice I got was from an older salesman I knew named Hal, when I first came into the fashion business on a big level. I remember him saying, ‘You have to save your money in this business because you never know — at one point or another, you’re going to have to bring it back and invest it back into the business.’ And he was right about that. ”

3. Liz Wessel, co-founder and CEO of WayUp

Best advice: Choose your career as you would your spouse.

”One of my friend’s dads told me at graduation that choosing a career should be taken as seriously as choosing a spouse, since you’ll probably end up spending more time in your job than with your spouse for the foreseeable future. ”

4. Ashif Mawji, CEO of Trust Science

Best advice: Stick to the basics when running a business.

“I have been fortunate enough to have had dinner with Warren Buffett and play poker with him for charity every year. Warren told me that keeping things simple and focusing on the basics is a key differentiator.

“His simple and pragmatic approach to investing, as well as everything else he does — with simplicity being paramount — has helped me clear the confusion, complexity and noise that comes from running a business, and helped me focus on the big picture. Keeping things simple also helps with being first to market and providing a product that people can grasp and use. ”

5. Koel Thomae, co-founder of Noosa Yoghurt

Best advice: Just go for it.

“I was working for a start-up beverage company called Izze, and I had been obsessing about this yogurt and really trying to figure out if I was actually going to do it. One of the best pieces of advice came from my boss at the time. He said, ‘You should just go for it. You’re obsessing about this yogurt, so just go for it.’”

6. Chris Fanini, co-founder of Weebly

Best advice: Don’t be afraid to push the boundaries.

“It’s better to beg for forgiveness than to ask for permission. It’s more about pushing boundaries — not as much about abusing the situation, but knowing when to push the boundaries. That’s something my parents always told me growing up.”

7. Jim Estill, CEO of Danby

Best advice: Fail often, fail fast and fail cheap.

“Having a failure does not make you a failure. The advice was from my father. Over time, I morphed that to, ‘fail often, fail fast, fail cheap,’ and came to realize that people and companies that fail, win more. ”

8. Allison Page, co-founder and head of product of SevenRooms

Best advice: There is no substitute for hard work.

“I learned the most valuable business lessons on the field as an athlete. There is so much you can learn from being a part of a team, and working towards your goals, both together and individually. The advice can really be summed up in two words: Work hard.

“I picked up early on that nothing will make up for the hours you spend hustling and working towards your goals — whether it’s as an athlete on the field, or as an entrepreneur building a business. Nothing comes easy in business or in life, and you have to work for it every day.”