Confidence is a fine trait. Over-confidence isn't.
I sometimes have an over-confidence that can be viewed as arrogance.
Whatever you say, say it with conviction
Over-confidence is as evil as undue anxiety.
I am afraid to show you who I really am, because if I show you who I really am, you might not like it--and that's all I got.
Beware of over-confidence; especially in matters of structure.