When I took the step up from intern to part-time employee at the start-up I work for, my boss sat me down for a talk. “You’re a great worker,” she said. “But my problem with you is that you’re so quiet and passive. You need to be a more assertive speaker, or you’re not going to get anywhere professionally.” These words were devastating to me. Sure, growing up, I had my teachers and friends pointing out how quiet I was. But they never outright called it a flaw—just implied that it was something that made me different, that made it difficult for people to figure me out. Here my boss was, however, telling me that my silence was a problem—one that would negatively impact my future.

Later that day, I had a talk with a friend, who assured me I shouldn’t let my boss convince me that my quietness was a flaw: “You’re just an introvert. You speak when you have something to say.” Still, I couldn’t sit in the office without stressing about how little I spoke during meetings. I stressed about it so much that I had no energy left to actually do the most important communication work: thinking of things to say. For months, I worried that my boss was watching me, listening to my every word, and waiting for me to take her words to heart.

And I did take her words to heart. I took them to heart and turned them into an opportunity to teach and open minds. One of the most important functions I serve in the company is running its blog, so I wrote a post about my lifelong struggle to see my quietness and my very small reserve of social energy as a strength. In the post, I argued that my ability to listen and to think deeply is what makes me unique.

When once I desired nothing more than to write a letter to everyone in my life, apologizing for not speaking to them as much as I thought they deserved, Cain’s book made me realize I no longer had to be apologetic. I declared a new life goal (on Facebook, too, because typing a Facebook status is obviously easier than telling people face-to-face): “Never apologize for all of my quiet again.” And I’ve gained the confidence to approach my social battles strategically–I can take improv classes and participate in eight-minute-long scenes in front of an audience of twenty people, so long as I conserve my energy somewhere quiet before and after the class or performance. Now, I can dedicate as much energy to writing as I did during my most solitudinous, pre-driver’s-license high school summer vacations by getting up with the sun and giving myself a roommate-less living room space in which to work. Rather than feeling excruciatingly conflicted, I easily turn down a lunch or dinner offer if I know I have a party, show, club meeting, or other equally exhausting evening activity on the agenda. And I can even post “Read More”-length arguments on Facebook championing the legitimacy and strength of the quiet, introverted, and/or socially anxious–so long as I ban myself from checking my page for the next three or four hours.

Surprisingly, my boss took the sentiment in my essay seriously. A month or so after the post went up, as she gave me a more managerial role in the company, she told me, “I’ve been thinking a lot about quiet leadership, and I’m really interested in seeing how that plays out in a small office like this.” Hearing that was extremely gratifying. To know that I’d broadened the mind of one of the most high-energy go-getters I know—to know that, just by telling my story, I was making a difference and helping people become more understanding of how diverse personalities are—was extremely gratifying. I’d never been more proud to call myself an introvert.