I once was talking about a coworker behind his back.  It wasn't necessarily an awful conversation; but what I didn't know was that he was working in the next room with the door open.  He approached and asked what I had been saying.  I knew I was caught.  I was so disgusted with myself.  
The other week, I was talking about a co-working of mine - okay, I was gossiping..  
user
Hmm, how did that make you feel
assistant
Pretty awful, actually.  Especially considering that the coworker of whom I was speaking was in a room just next door with the door open.  
user
Yeah, at least now you're more aware, it can be pretty tough when you're trying to break the habit though
assistant
Absolutely.  I really am disgusted with myself.  I don't know why I open my big mouth!
user