What do I say about why I left my last job? - what worked for you?

They always ask why I left, and I freeze. This is my first time dealing with any of this. I have been practising in the mirror. Do you mention numbers?

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

Thanks for writing this out. I went through something close to it last year, and it settled down once I kept a simple log of every call and form.