Robert Stevens
Robert Stevens
Company: Lockheed Martin
Fortune 500 Rank: 58

Robert Stevens enlisted in the U.S. Marines when he was 18 years old, which he regards as the most important leadership decision he made. During his 2010 acceptance speech for the General John LeJeune Recognition for Exemplary Leadership, he mentioned that an MBA student at Columbia once asked him about the most important lesson he learned in business school.

"I gave it to them directly," Stevens said. "I did not learn about leadership in business school. I learned about leadership when I was 18 years-old and first introduced to the United States Marine Corps, where leadership is not taught by a favored professor in a three-credit hour course, it is taught by every officer and every NCO in every minute and every hour of every day, in every action, every word, every deed, and every circumstance."

Now, almost one in every four Lockheed Martin employees has served in the military. "But we don't hire veterans because I'm a veteran. We hire veterans because it's good business," Stevens tells Fortune. "They have courage, integrity, honor and character. And they understand service and sacrifice in the interests of others. All that makes them good for our company and good for our business. It's the right thing to do, and frankly, it's the very least we can do."

By Shelley DuBois, writer-reporter - Last updated May 07 2012: 9:53 AM ET