I'm deep in the midst of midterm-marking, but I noticed something that I do in my self-talk about my teaching abilities:
When I have a good day with the students, I think "Hey, today went well!" but when it's a bad day I think "I'm terrible at teaching and my students are probably disappointed that they decided to take this class from me!"
When a student does well on a midterm I think, "What a clever student! He/she really gets it!" but when a student gets a low mark I think, "I did a terrible job of teaching this! Was I really unclear that day?"
Huh. Apparently I treat the good things as nice little aberrations, or things outside of my control, and I treat the bad things as being The Norm, and There's Something Wrong With Me.