Nucor CEO John Ferriola has worked in the steel business since he graduated from college in 1974. He first started at Bethlehem Steel, where he worked for 17 years, before moving on to Nucor. There, Ferriola quickly moved up the ranks to become CEO of the nation’s largest steel company. Nucor is ranked number 170 on the Fortune 500 with revenues of more than $16 billion.

What was the key to his success? Ferriola tells Fortune’s Susie Gharib he was guided by two “great leaders” over the course of his career. They taught him important leadership lessons, including “Work hard, work harder, and then work hardest.” And they also emphasized the importance of trusting, respecting, and empowering your team.

“If you do all of that,” Ferriola said, “you’ll be a good leader.”