My first year in sales, many years ago, I was awkward—and a slow learner. But my first sales manager, Guy Campbell, must have seen some potential because he invested a lot of time in coaching me. When Guy joined me on a customer meeting, I noticed he had a habit of pulling out a coin and placing it in the palm of his hand.

I didn’t think anything of it until about three years later when I was promoted to sales manager in another office. Soon after, I ran into Guy and asked him why he always put a coin in his hand when he was out in the field with me. He responded, “Well, Kevin, when you were starting out, you were not very good. But I knew that in order for you to learn and improve I needed to keep my mouth shut. I couldn’t jump in and take over every time you got in trouble. The only way I could keep silent was to squeeze that coin. The worse and worse you did, the harder and harder I squeezed. I needed to create a point of personal pain that was greater than the pain I felt watching you screw up a meeting!”

I’ve carried Guy’s wisdom with me for many years and, mentally at least, squeezed a lot of coins in my day. And while I’m doing that squeezing, I’m taking note of the issues I want to talk over with the sales rep after the meeting. It’s only by observing that I can properly evaluate what the problem is and offer suggestions that will lead to lasting improvements. Being able to start off conversations with my reps with descriptions of specific issues I had observed transformed me as a leader, and ultimately their effectiveness.

What matters most in terms of results is not how effective your reps are when you’re right there working with them, but how effective they are when you’re NOT there. As Confucius said in 451 BCE, “What I hear I forget. What I see, I may remember. What I do, I understand.”  Your salespeople will learn by doing, and you can speed up their learning curve by allowing them to make their own mistakes. So make sure to have a quarter handy the next time you do a ride-along or sit in on a meeting or teleconference with a client.

Kevin F. Davis is the author of “The Sales Manager’s Guide to Greatness: 10 Essential Strategies for Leading Your Team to the Top.” Kevin is the president of TopLine Leadership, Inc. which specializes in sales management development and custom sales training.