Your job as a leader is to make people uncomfortable. Pursuing ambitious goals, confronting significant challenges, and moving into uncharted territories—all of which leadership often entails—require people to embrace discomfort.

In my new book, Leaders Open Doors, I explain that the central function of a leader is to be a creator of opportunity. The opportunities you provide as a leader should be outside of those areas where a person already feels comfortably skilled. For example, inviting an employee to join you in a client presentation, asking a direct report to lead a meeting in your absence, and bringing a mentee into the midst of a risky decision you’re facing all qualify as uncomfortable, skill-stretching opportunities that a leader can use to develop people.

Virginia “Ginni” Rometty, the CEO of IBM, says, “Growth and comfort don’t coexist.” People grow, progress, and develop in a zone of discomfort, not comfort. It is in the pursuit of challenges that are hard, scary, and uncomfortable that people discover their worth and convert potential into actual skills.

Because of this, a leader has two critical jobs: First, a leader has to model a willingness to move into her own discomfort zones. In the course of her career, for example, Rometty had a history of purposefully seeking positions where, for a little while, she was “in over her head,” and the only way to stay afloat was to work extra hard at being successful in the new position. It’s easier to move into our discomfort zones when we’re following a leader who is already there.

Second, a leader must nudge people into their discomfort zones so that they stretch their skills and capabilities. The idea isn’t to get people to do wildly uncomfortable things, but rather willfully uncomfortable things. Some excitement, in the form of sweaty palms, is good; paralyzing fear is not. If you shove people too far into discomfort, their performance will suffer, and they’ll resent you. It’s important employees understand that you’re asking them to do uncomfortable tasks to promote their growth and career advancement. In other words, the discomfort you’re encouraging them to embrace is purposeful, not foolhardy.

To be clear, when it comes to learning and development, comfort also has its place. Once a leader has nudged a person into discomfort, she has to allow that person enough time to gain confidence and mastery over new skills. For example, an employee who has been nudged into accepting a new role that is outside of his current area of expertise needs time to settle into the new role. He also will need training in the aspects of the job that are least comfortable, as well as active support from the leader.

The trick is for a leader to develop people by modulating between comfort and discomfort. When people are too uncomfortable or fearful, the leader must throttle back and give them time to master new skills. Once the proficiency is gained, it’s time to nudge people back into discomfort. By maintaining this fine balance, complacency and apathy can be reined in, and people will keep growing—in both the service of their careers and the goals of the organization.

Learn more about how leaders create growth through opportunity in Bill’s latest book, Leaders Open Doors, available for pre-order. Bill is donating 100 percent of the book royalties to programs that support kids with special needs.