As a very new teacher I had a (girl) learner giving me a hard time in class.  Sarah was a buxom lass, just as tall as I.  I didn't realise it at the time, but my right hand was twitching - wanting to strike her.  
She noticed it.  She looked at me levelly and said: "Strike me, Ma'am, and you have lost your job!"   
That broke the tension and we both just let it go.
However, I went home and reflected on it for a long time.  I had been trained never to hit a learner, but I now realised that - somewhere in the back of my mind - I did think that I could hit someone - as a 'last resort'.   I was shocked at me, and I had to accept that shame before I could move forward.  
That long afternoon and evening (and many times since) I had to think of strategies which I could use to get the 'Sarahs' of this world to do what I wanted them to do - and be happy about it!   
This was one of the best confrontations that I ever had. Forty years later, I am grateful to Sarah.