The closest I ever cam to missing a flight was about 20 years ago. I was flying to a friend's wedding (BOS-RDU). I got to the gate with plenty of time to spare. While waiting at the gate, I was watching the NCAA tournament - my two alma maters were playing each other. Next thing I know, I turn around and they're closing the door! I jumped up and got their attention to hold it for me. Lesson learned - always pay attention.