I make a lot of lists. It's an old habit that I started when I was in grade school. Lists of to-dos, lists of goals, lists of workouts. Lists, lists, lists. 

I'm also a nostalgic person, so I tend to save a lot of these lists and use them as touch points for storing memories and keeping track of the passing of time. Every now and then I'll come across an old list and re-read it. Some of them make me think deeply, while others make me laugh at my younger self's absurdity.

Recently, I came across a list in my desk labeled simply “Mentors.” I've had a lot of mentors in my life--many who may not even know they played this role for me. I've always kept an eye on them and noticed the choices they've made and how they've carried themselves personally and professionally.

A number of years ago, I drew up a list of my mentors as it helped crystallize who I truly admire, why I admire them, and what I could learn from them. It was fun to stumble upon that list recently and reflect on my choices.

But, as I read an interview with my friend Barb Goose, the president of Digitas, in which she talks about reverse mentors, I was inspired to draw up a new list.   

Reverse mentors are people younger than you who you admire and learn from. Looking back, I found that everyone on my mentor lists were older than me. That was my traditional definition of a mentor--someone ahead of you in life who inspires you, helps guide you, and shows the correct way to live.

When I read Barb's reasoning to seek out reverse mentors--younger folks who she learns from in this rapidly changing, digital world--it really resonated with me. Entrepreneurship, technology, and innovation are profoundly influenced by youth. If you're not tapping into their knowledge base and seeking their insight on trends and opportunities, you're missing out on a valuable resource. 

Upon reflection, it's one of the reasons I enjoy teaching so much at Harvard Business School. I learn a tremendous amount from the students. They're always helping me to think about the latest disruptive ideas, technologies, and companies that are emerging. They also challenge me to find the best way to build a start-up and tackle opportunities.

So, now I have my reverse mentor list. I'm tucking it away in my desk for another few years and look forward to tracking the careers and choices of those on it.

This post originally appeared on Jeff Bussgang's blog, Seeing Both Sides