Every time I've been hired for a full-time job in the last 20 years, I've made it a point within my first week of starting to ask my new manager some variation of the following question:
"At what point during our interview did you know you were going to offer me this job?"
Most of the responses I've gotten have been enlightening, and all of them have helped me better articulate my unique value proposition over the years to position myself in the best possible way.
Many years ago, my "one-up manager" told me the moment I earned a highly-coveted summer internship with Procter & Gamble during university happened after I made a spontaneous, self-deprecating joke about my atrocious high school calculus grade.
The fact that my punchline made him and his two colleagues burst out laughing (one of them so hard, he had tears!) wasn't the only reason I got that job, but that exact moment showed I was self-aware about my "opportunity areas" and didn't take myself too seriously... and that ended up being the tie-breaker amongst everyone else competing for the position.
And what did I learn from that?
That showing some personality during an interview can be a good thing! If they like you, they like you, and that's an advantage in the process. And if they don't like you... do you think you're going to be happy working there if you were somehow offered the job? (Probably not.)
I've been "authentically me" during interviews ever since, for better or for worse.
That's just one example; there have been many more. And the lessons have all come because I took the time to ask the question and learn why I had succeeded.
We tend to dwell on our failures.
When something goes wrong at work, it's common to hold a "post-mortem" with everybody involved to understand exactly what happened and what can be done better the next time around. Post-mortems can be extremely valuable.
But let's not forget to reflect and learn when things go well too.