Recently, here at Inc.com, I've written about my experiences as a consultant in my 20s and early 30s, as well as those of Lonely Planet's 26-year-old CEO.

But what might we learn from those who started a successful business young but are now veterans with decades of experience? I decided to turn to a client of ours at Peppercomm, Citrin Cooperman, for some thoughts and reflections.

Niles Citrin and Joel Cooperman started their accounting, tax, and consulting firm in their mid-20s, with three employees. Now, having just celebrated the company's 35th anniversary, they manage a team of about 675.

Citrin and Cooperman have spent almost their entire professional careers in leadership positions. For those who may find themselves in high-level positions at a young age, or who strive to find a fast track to a leadership or strategy role, they passed along eight vital lessons they've learned:

  1. Remember: People Are People, Not Demographics. An overemphasis on someone's age and tenure loses sight of who they are as people--boomers and Millennials alike run the risk of being typecast by age in ways that don't reflect who they really are and what they have to contribute. "Leaders must look at their people not as an age but as individuals," Citrin says. "You have to look at each employee to utilize their talents and help them grow, develop, and understand who they are."
  2. Borrow From Those Around You. Cooperman says he became a sponge and picked up the best skills from those around him. He was shy, but he learned how to project himself by watching charismatic co-workers: "As I mentor young people today," Cooperman says, "I tell them to do the same: Take things they really admire from others and make them their own."
  3. Find a Mentor Who Will Push You to Grow as a Leader. Citrin emphasized his enjoyment of working with young people "who are sponges" as well. "It really makes me want to sit with them and teach them everything I can," he says. "People did it for me; I want to do it for them." Citrin's father brought him into the family business to keep the books as a teenager. When his father sold the business, Citrin began working with the accountant, who took over the books and pushed him into client-facing work. At 24, Citrin began managing a relationship directly with a senior leader of a major client at a Big 8 accounting firm. "They didn't ask me if I wanted to do it; they threw me into the fire," says Citrin. "But ever since that experience, I find myself comfortable in every situation and every setting."
  4. Don't Forget That People Are Looking to You for Leadership. The firm's first employee was almost 20 years older than Citrin and Cooperman, and most of their employees had more tenure in the industry than they did. But the two partners reminded themselves regularly that their employees were there because they wanted to be on the Citrin Cooperman team.
  5. Empathy Is Key. Citrin says that young leaders must be able to put themselves in the mindset of those they are working with to understand who those people are and what they want to do. "Sometimes, a leader makes the mistake of thinking everyone else thinks the way they do and that everyone has the same ambitions," he says, emphasizing that the age of a leader isn't an issue if she or he acts as a catalyst to help the team grow and excel. Cooperman shared that one of his earliest lessons as a young leader came when an employee thought he was mad at him because he hadn't said hello one morning. "I learned to say hello and goodbye, no matter what's on my mind," Cooperman says. "The guy who runs the company has to be upbeat, communicative, fair, and consistent. If I follow the same rules they do as the CEO and managing partner, then it's logical to expect them to as well."
  6. Actively Look for Unexpected Opportunities. Cooperman's first job out of school was for a New York City accounting firm. He wasn't planning to stay in accounting for more than a couple of years, but he ended up in the firm's nascent mergers-and-acquisitions department, with only one other person working above him. Helping build the M&A division in a hands-on fashion gave him a chance to learn business strategy and gain quick experience in how to build a practice. "It was a shotgun education that propelled me along much faster than if I was in a very traditional accounting role," Cooperman says. Four years later, Cooperman was an M&A and due diligence specialist who co-founded his own firm. "You don't know where your career will lead you," he says, "and you have to have an open mind."
  7. Speak Authentically About What You Know. Citrin is a believer in the philosophy that "people will respect you if you sound smart." However, he adds an important caveat: "You sound smart if you are. People who know what they are talking about are happy to share information. Those who are full of bluster probably won't want to, for fear of being found out that it's only bluster." Of course, leaders don't have to know everything; instead, they should speak about what they know, be honest, and seek answers when they don't already know. According to Citrin, "You have to know when to say, 'I'll get back to you,' rather than talking as if you know what you're talking about when, perhaps, you don't."
  8. The Only Way to Succeed Is to Fail. Cooperman says he has built his career on the perspective that you have to deal with failure in an honest way and without rationalizing it if you want to truly learn from it. "I've done some things that would not go onto my highlight reel," he says. However, he says, a fear of failure leads to an inability to pursue new approaches--which is vital for a leader to grow and remain relevant. "I'm 61 years old, and it amazes me how much I still learn about management after 35 years of doing it," Cooperman says. "You only have one shot at this. You have to cut loose and let go."