What do I say about why I left my last job? (update)

I have an interview next week and I am unsure how to explain why I left my last job as a call-centre agent. I would rather hear the honest version than the polite one. I do not want to blame the company. What do you say?

Practise it out loud with a friend. Mine felt natural after the third try.

Say it plainly and move on to what you can do. Interviewers usually move on if you do.