Very few people succeed in business without a degree of confidence. Yet everyone, from young people in their first real jobs to seasoned leaders in the upper ranks of organizations, have moments — or days, months, or even years — when they are unsure of their ability to tackle challenges. No one is immune to these bouts of insecurity at work, but they don’t have to hold you back. “Confidence equals security equals positive emotion equals better performance,” says Tony Schwartz, the president and CEO of The Energy Project and the author of Be Excellent at Anything: The Four Keys to Transforming the Way We Work and Live. And yet he concedes that “insecurity plagues consciously or subconsciously every human being I’ve met.” Overcoming this self-doubt starts with honestly assessing your abilities (and your shortcomings) and then getting comfortable enough to capitalize on (and correct) them, adds Deborah H. Gruenfeld, the Moghadam Family Professor of Leadership and Organizational Behavior and Co-Director of the Executive Program for Women Leaders at Stanford Graduate School of Business. Here’s how to do that and get into the virtuous cycle that Schwartz describes.