"You need both self-confidence and self-doubt to do your best work. A little self-doubt can keep you humble enough to realize you may need to learn more or work harder at something. It may even give you the dogged determination to keep going and show people what you're made of. Doubt, causes us to question what we're doing, mentally prepares us to accept change, propels us to work harder or differently, and can lead to us taking more cooperative approaches in dealing with people who disagree with us."

— Alice Boyes, The Healthy Mind Toolkit