He was an active researcher contributing to our knowledge.

CNN: Why we chase storms

Unlike most business owners who spend significant time in their industry and just focus on what they know, serial entrepreneurs are active in many industries and need to acquire knowledge about a variety of businesses and sectors.

FORBES: Serial Entrepreneurs Are More Successful

Hence, do keep an active, open mind and door, and let knowledge flow in, even if you think you are currently doing just fine.

FORBES: Big Firm Innovators: What Large Companies Can Do to Be Just as Innovative as Small Entrepreneurial Ones

They understand that index fund portfolios outperform portfolios using active funds almost all the time and use this knowledge to increase their portfolio performance.

FORBES: Index Fund Buyers are Skilled Investors

Although retired executives have more time than active executives to devote to board matters, their knowledge of industry dynamics and regulations is potentially outdated.

FORBES: Warren Buffett, And His Board, May Be Too Old To Run Berkshire Hathaway

Considering the extremely large proportion of practitioners active around the world and the even larger population calling on their knowledge, traditional health care raises fundamental questions and requires specific reflection to deal with its ethical implications.

UNESCO: Social and Human Sciences

Volunteer work in your passion, a side business in your passion, an encyclopedic knowledge of your passion, and an extensive network of contacts active and influential in your passion are examples of ways to tangibly demonstrate your passion.

FORBES: Follow Your Passion Is Bad Career Advice For Most People

Rob Jesmer, the former executive director of the National Republican Senatorial Committee, is especially active on a day-to-day basis, said one person with knowledge of the matter.

WSJ: Facebook's Mark Zuckerberg Starting Political Group