For me, lack of self-confidence is actually a good thing in poker. It makes me study and work more to improve my game.
Things change when I have had profitable days and nothing can stop me. Today I realized it, I had a losing day after a long winning streak. I am sure it is because of over-confidence. I played way too loose (I am still at low stakes), also I tried too advanced moves against clueless fishes, and it went against me.

Tell me what other signs there are that tell we are playing too confidently? Mainly I need information about differences between HUD stats.