Ask HN: What is the most impressive thing "other than this startup" you've done?

Resubmitted for more answers.

I'm not asking to start a posturing or bragging contest. I'm actually curious to see some kind of sample of impressive things. I've already submitted my own answer on the application, I wonder what variety of things people have answered on their own. pg - If this amounts to some sort of cheating, please let me know. That's not intended. On another thread I saw someone talk about their interest in other people's answers and realized I am as well.