Brené Brown, Daring Greatly: How the Courage to Be Vulnerable Transforms the Way We Live, Love, Parent, and Lead 2 (2012):

Vulnerability is not knowing victory or defeat, it’s understanding the necessity of both; it’s engaging. It’s being all in.

Vulnerability is not weakness, and the uncertainty, risk, and emotional exposure we face every day are not optional. Our only choice is a question of engagement.

. . .

Perfect and bulletproof are seductive, but they don’t exist in the human experience. We must walk into the arena, whatever it may be—a new relationship, an important meeting, our creative process, or a difficult family conversation—with courage and the willingness to engage. Rather than sitting on the sidelines and hurling judgment and advice, we must dare to show up and let ourselves be seen. This is vulnerability. This is daring greatly.