The simple request came in an email, asking me to provide some thoughts about the importance of mentorship. A story about someone who helped me become a better leader.

Thinking back over two careers—my long time in the Army and a shorter time in the health care industry—hundreds of faces appeared in my memory’s eye. General officers like Fred Franks, Eric Shinseki, Larry Jordan and Herbert Lloyd delivered phenomenal guidance and helped me grow, as did command sergeants major like Roger Blackwood, Thomas Capel and David Davenport. Several drill sergeants and even a few privates and young sergeants acted as “reverse mentors,” providing what Harvard Business Review suggests is important information that helps old guys like me bridge generational gaps with younger soldiers. Many doctors and nurses—they know who they are—continue to serve me as trusted mentors as I serve in a new career field today.

All contributed to my leadership growth.

But there’s one who stands alone in this pantheon of mentors. That’s retired Chairman of the Joint Chiefs of Staff (and former Chief of Staff of the Army) Gen. Martin Dempsey. The trust we’ve built since we first met 40 years ago as triplex neighbors and professors at the U.S. Military Academy at West Point, New York, continues to grow. He is the one I turn to when I face a difficult professional or personal challenge, and his sage advice still influences my leadership growth.

Hanging on His Words

When we met in 1984, then-Capt. Dempsey wasn’t a graybeard. He didn’t at all represent the original Mentor who provided guidance to Odysseus’ son Telemachus in the Odyssey, but he was unique in his maturity and wisdom.

After cutting the grass and grabbing an adult beverage on any given Saturday afternoon, we’d sit on our back porch and opine on how we would fix the Army’s problems and how we would lead our soldiers with aplomb when we returned to the “real Army.”

I was always impressed by his philosophy, and I grew by paying close attention to his words. He was what I later learned business researchers describe as a peer mentor: one who is similar in age, professional and personal goals and service objectives from whom a mentee can gain knowledge and growth. After leaving West Point and returning to the Army, we stayed in constant contact and remained best friends. And I increasingly reveled in his professional mentoring.

In the coming years, we’d share more adult beverages and family reunions—our wives and children were also close—and I’d always seek his advice and guidance. We went to Operation Desert Storm together—he as an executive officer of an armored brigade, me as the operations officer of a cavalry squadron, both flowing out of Germany—and when we returned, we had many in-depth discussions about what our units had done. He finished battalion and brigade command when I was just beginning, and he provided insight on what he found successful and what traps I should avoid. Following him as the armor branch chief at the U.S. Army Human Resources Command, we both had a better view from that exceedingly stressful job of how to best develop our officer corps professionally.

Boss Takes Over

We would both become brigadier generals—again, a year apart—and my friend and mentor would become my boss three times in the next 10 years. As his assistant division commander in Baghdad, I have numerous pages in my green notebooks filled with lessons I learned from then-Maj. Gen. Dempsey’s (it was never “Marty” now) combat leadership.

When I took command of the same 1st Armored Division a few years later, the mentoring he gave me, the command sergeant major and the brigade and battalion commanders significantly influenced my leadership style, because that is the legacy mentors leave. A few years later, newly promoted Gen. Dempsey became commander of the U.S. Army Training and Doctrine Command, and I was assigned as his deputy commander for the U.S. Army Center for Initial Military Training, a position he created to standardize basic and individual training for enlisted soldiers and officers.

Dempsey soon would be appointed as the chief of staff of the Army, and I would become commander of U.S. Army Europe. During a dinner with our commanders and staff in Heidelberg, Germany, Dempsey reminded me of our conversations as young captains about how we would “fix” the Army if we were ever in charge. “It’s a lot harder when you’re in the job,” he said.

For me, Dempsey is the epitome of the perfect mentor. We’ve built mutual trust. He’s encouraged my growth through professional guidance with candid and unvarnished constructive feedback. He’s contributed to my leadership style and given me new perspectives from his experiences that have formed mine, and he has caused me to reflect on both my professional and personal life (did I mention he also models incredible husband and father skills?).

Humor and Wisdom

How did he do all that? He’s humble, and that shines through in every one of our engagements. He’s smart. He thinks through what his guidance will be, and he provides succinct recommendations for how I should address situations or how I might act. He inserts humor and wisdom into every conversation, usually with a mischievous twinkle in his eye and a slight Irish grin, and his advice always makes me smile. I always marvel at his pragmatic wisdom. He takes his mentoring, but not himself, seriously. That’s the mark of not only a terrific mentor, but a true friend and great leader.

As much as I admire Dempsey as a mentor, I also give him credit for helping me provide mentoring to others. It’s important to be mentored, but it’s just as important to learn from your mentor how to inspire others to be the best they can be. Because that builds the bench for the future. I sincerely hope I have mentored others the way this great leader has mentored me.

Lt. Gen. Mark Hertling, U.S. Army retired, commanded U.S. Army Europe in 2011–12. He also commanded the 1st Armored Division and Task Force Iron in northern Iraq during the Surge. He is an Association of the U.S. Army Center for Leadership fellow.