I recently had the pleasure of sitting down with 91-year-old entrepreneur Jack Nadel to ask him how he has been able to achieve sustainable success in a wide range of industries over a 70 year span of time.

Nadel started his first business venture immediately after World War II and went on to found, acquire and operate more than a dozen companies worldwide that have produced hundreds of new products, thousands of jobs and millions of dollars in profits. Over the course of years, Nadel has also built up the Jack Nadel International multi-million dollar empire, a promotional merchandise distribution.

Because of his success, my seven-hour and three-day mentorship session with Nadel provided me with countless actionable and invaluable business tips, strategies and advice. Here are three particularly valuable lessons Nadel shared with me:

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Find a need and fill it.

Nadel stressed to me that finding a need and filling it is his best and most important advice. He explained to me that this advice applies to both product and service-based businesses, startups or giant corporations. “Success is in finding a real market need and filling it," he said. Nadel pointed out that his adherence to this lesson has allowed him to enjoy success in multiple industries over the past 70 years while many other businesses and aspiring entrepreneurs around him were struggling or going out of business.

Don't let your ego get in the way.

Nadel emphasized that in order to achieve massive success as an entrepreneur you must be receptive to coaching, know your numbers and do your research. He warned, “There’s nothing quite as exciting as a new idea, especially when you’re convinced the idea is worth a million bucks, or more, but watch out. Great ideas are rarely born fully formed, and a new idea is like a 2-year-old: loud, self-centered and completely without perspective.” Having consulted with thousands of entrepreneurs all around the world, this lesson really resonated with me, because I see egos getting in the way of most entrepreneurs every day.

Remember: the business idea or concept you are considering right now is not the first or last incredible business opportunity that you are going to come across. The billionaire success story Richard Branson was correct when he once said, “Business opportunities are like buses, there’s always another one coming.”

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Most successful entrepreneurs aren't geniuses.

As a business consultant and the founder of Thrive15.com, I constantly run into people at conferences and in workshops who don’t feel like they are worthy of success, or have the mental capacity and the connections needed to achieve success because they are not geniuses. However, this is not the case. “Every generation will produce technology pioneers like Steve Jobs, Bill Gates and Elon Musk, who invent revolutionary new products and services," says Nadel. "They seem to have a genetic pre-disposition toward genius, but for the majority of us, the non-geniuses, the best solution is still to be entrepreneurial, even if only to earn enough income to cover the difference between expenses and earnings.”

He went on to say, “I speak from seven decades of experience, which have provided me with knowledge that is invaluable in an ever-changing market. I've lived, learned and profited knowing that every down stroke has an upstroke, and there is money to be made in either situation.”

Whether you are a current entrepreneur or an aspiring one and regardless of what industry you are in, I encourage you to apply these three lessons to your own life and business.

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