A report from researchers at Duke University sounds an alarm about the anxiety and depression among female undergraduates who aspire to “effortless perfection.” They believe they should display perfect beauty, perfect womanhood, and perfect scholarship all without trying (or at least without appearing to try).

Optimism sets a different machine in motion. Especially in difficult moments, the people you lead need to feel confident in your ability to focus on what matters, and not to operate from a place of defensiveness and self-preservation. This isn’t about saying things are good when they’re not, and it’s not about conveying some innate faith that “things will work out.” It’s about believing you and the people around you can steer toward the best outcome, and not communicating the feeling that all is lost if things don’t break your way. The tone you set as a leader has an enormous effect on the people around you. No one wants to follow a pessimist.

A pessimistic explanatory style—the habit of believing that “it’s my fault, it’s going to last forever, and it’s going to undermine everything I do”—is debilitating, Seligman found. It can diminish performance, trigger depression, and “turn setbacks into disasters.

Optimism, it turns out, isn’t a hollow sentiment. It’s a catalyst that can stir persistence, steady us during challenges, and stoke the confidence that we can influence our surroundings.

Courage, the saying goes, is not the absence of fear but the ability to act in the presence of fear. Katherine Graham lived and led with fear and anxiety that would never fully abate, no matter how successful, or powerful, or famous, or wealthy she might be or become. Warren Buffett described her as marching forward with knocking knees. Ben Bradlee related that she talked about worrying awake at night, “picking the wool off the blankets.” She paid a hefty Stress and Drudgery Tax, not just in leading through dramatic episodes, but also in shouldering the more routine duties of effective leadership such as giving speeches. Even the prospect of making remarks at the staff holiday party would loom for days or weeks ahead of time, filling her with dread. Graham herself copiously conveyed her inner turmoil; I quick count across her memoir yielded some permutation of words of fear or anxiety (for example, “dread,” “terrified,” “anxious,” “worried,” “fretted,” “frightened,” “nervous,” “anguish”) 289 times in reference to herself.