A tough boss may be challenging, demanding and even downright mean. But according to bestselling management author and CNBC contributor Suzy Welch, that doesn't mean they're bad for your career. In fact, knowing the difference between a tough boss and a bad boss can be crucial to your success. Welch says she learned this lesson as an intern at The Washington Post in 1981, while working for award-winning journalist Bob Woodward. ("Yes," she says, "that Bob Woodward.") Welch had arrived for her internship in awe of Woodward and his reporting on the Watergate scandal, which earned him a Pulitzer and inspired a movie, but she tells CNBC Make It that initially, "I thought Bob Woodward was a terrible boss that summer because of how hard he made my life."

CNBC Contributor Suzy Welch

He routinely pushed her to go back to her sources for more information, and questioned everything she wrote. "He did not engage in pleasant banter," she says. "He never said, 'Good job,' even once when my story hit the front page of the Post — as an intern!" Welch recalls a time when Woodward bristled at her suggesting a time for a meeting, instead of asking about a time that was convenient for him. "In short," she says, "Bob Woodward intimidated me." But looking back, she says she now realizes that he was being tough on her "to toughen me up for the profession I had chosen. He didn't care about my feelings. He cared about my career."