One of my company's co-founders, Jeremy Weir, recently spent a weekend surfing with Uber co-founder Ryan Graves, enjoying talks about upending markets and fundamentally changing businesses.

He returned from the trip having had an epiphany and possessed a renewed sense of excitement as we prepared to launch into a new vertical. Because Jeremy typically works by himself in a remote office, Graves’ influence proved to be a huge asset.

It all proves that the company that a businessperson keeps can have a profound effect on him or her and subsequently the success of a business. 

Related: Getting Your Dream Mentor to Talk to You

Renowned businessman Jim Rohn once said, “You’re the average of the five people you spend most of your time with.” But it’s common for entrepreneurs to underestimate the importance of the company they keep. Bottom line: The people around you matter.

You need people -- whether it’s co-founders, mentors, family or friends -- who will challenge you and make you better, thereby raising your average or helping you maintain a high one. Many entrepreneurs strive to be the smartest person in the room on every issue. But if you're always the smartest person, you're hurting yourself. You want to surround yourself with people who can run circles around you in as many areas as possible, people who are exponentially better in a variety of ways.

Here’s the really hard part: Giving a silent critique of the people you keep around you may sound judgmental and downright ruthless, but understanding their influence on your performance is critical to your success. As an entrepreneur, you have too much at stake to let this go unaddressed. If someone is bringing down your average, you have to reduce his or her involvement in your life. Not doing so may hinder your energy, vision and ultimate success.

As an exercise, write down the five people with whom you spend most of your time. Assign a numerical value to each person from 1 to 10, and then calculate your average (with 10 being the most positive influence possible). How does each person affect your average? They don’t need to be Elon Musk or the Dalai Lama, but they should make you better. They should elevate both your thinking and performance.

When assessing your five people, consider the following:

Related: How to Filter Conflicting Advice From Multiple Mentors

Look outside of your company. Like Jeremy did with Ryan, you may need to seek out one person or more from outside your company. This is commonplace for many of the most accomplished entrepreneurs. For example, Nike’s founder, Phil Knight, promptly inserted the late Joe Paterno as his “hero,” after the passing of his business partner and mentor Bill Bowerman. Knight even described the process during Paterno’s eulogy in 2012. 

Be open to change. As you enter new stages, your five people may evolve. For instance, your five people in high school were probably very different than your five now. And it’s not as though the high school friends needed to be thrown out, but their roles may have diminished. True friendship always endures, and you’re simply focusing your valuable time most appropriately. Conversely, if there are people who you think will help you improve, make a concerted effort to spend more time with them.

Put yourself under the microscope. Be cognizant of whom you are helping, inspiring and holding to a higher standard. Most great relationships are symbiotic, whereby people bring out the best in one another. How can you do a better job or what else can you bring to other people's lives to help them? Is there even someone whose average you’re bringing down?

Related: My Mentor Is 30 Years Younger Than Me (and Taught Me 5 Incredible Lessons)