I don't know if there's one super-massive one.
Nothing that's been so dreadful that it'll affect me for the rest of my life.
My life just seems to be full of lots of minor, although equally regrettable and embarassing mistakes.
Saying things at the wrong time, forgetting certain things, not having the nerve to do something I really should have, etc...
If I had to maybe guess towards my worst quality which has led to the most mistakes, it's probably my almost crippling lack of self-certainty coupled with worry and shyness when I'm on my own.
