tl;dr: Being rejected from a job interview is often taken personally. This is an exhaustive list of why someone may not be hired and the nuances behind hiring decisions.
tl;dr: Two instances where the author endured emotional pain in her job - public speaking and transitioning from a CTO to CEO. In the former, she overcome the pain of public speaking by powering through it. This never worked for the second. As a result, she notes the importance of pain as a teacher and understanding the situations where you can lean into it.