What do I say about why I left my last job? after 16 years as a delivery driver

I have an interview next week and I am unsure how to explain why I left my last job as a delivery driver. I also do not want to seem like a risk. What do you say?

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

Keep everything in writing and save the confirmation numbers. It made the follow-up calls so much easier.