Have you ever had a job that you were completely incompetent or at least moderately bad at? Did you feel guilty about it or was your attitude more like 'LOL YOU HIRED ME SO I'M YOUR PROBLEM NOW'? Did you resign to save everyone the frustration of having to deal with you or did you stick around like the tenacious motherlover you are?
My current feelings on the matter fall somewhere in between. I'm not quitting my job but I'm afraid of getting fired.