What Was Your Biggest Career Mistake?

But I'm not here to talk about MY fuckups, thank you. I want to know about YOUR messy handling of career opportunities, the kind you constantly look back on and say, "If only I had taken that job, I wouldn't be scrubbing toilets today. I could have been polishing doorknobs!"

So make me feel better. Tell me your biggest career regret--and whether that one incident really made a difference in your life or it's all in your self-flaggelating imagination.