One CEO shares the best piece of leadership advice she's ever received

Linda K. Zecher knows a thing or two about leading diverse teams.

Prior to her current position as CEO of publishing house Houghton Mifflin Harcourt, she fulfilled a variety of leadership roles, from leading a team of geophysicists to heading Microsoft's first US public sector division.

In a recent interview with Adam Bryant of the New York Times, Zecher shared the number one piece of leadership advice she ever received.

This pearl of wisdom came to her right after she had graduated from Ohio State University and landed her first job at Texas Instruments.

"A mentor of mine there was a former admiral. He told me, 'Every day when you go to work, you should ask yourself, What am I going to do for the fleet today?," she recalled. "And every day when you go home, you should ask yourself, What have I done for the fleet today?'"

She gained a few major takeaways from her mentor's advice that she has continued to apply throughout her career.

Firstly, leave your ego behind, and consider the entire "fleet" when making decisions - you're not the only person who matters: "I have no tolerance for people who need to establish that they're important or had some big important job," Zecher said. "No one cares."

Secondly, "It's not what you've done in the past that matters; it's what you're doing right now," she told Bryant.

She tells Business Insider she has always kept this advice in the back of her mind. "I like to ask myself at the end of each day, 'What did I do for the fleet? Did I add any value? Did I move the bar? Or did I have a wasted day?' I also tend to be a workaholic and this became a good way to set boundaries. I assess my day, and can then let my work go and enjoy family time."