I’m surprised you retired. ;)
In fact I worked about that long as well. It was mostly fun. Interesting work with very talented people. But retirement is better. Do anything you want any time you want - just like kids get to do before they start to school.
I call it playing because the feeling is the same.
That meant they were the largest civilian employer in America and at the same time the smallest federal agency (in terms of regulatory forms of governance).
Headquarters ran the post office through rule books and precedents.
What's not to like in that kind of operation. You could get to handwriting analysts with decades of experience just by walking downstairs. There were economists wandering about with several graduate degrees. There were top end statisticians doing cutting edge work. Lawyers all over the place who'd done quite interesting work and were willing to educate you on how to prosecute a trucking company. Then, for a while, I had a job where we'd be out there on the tarmack at night running around in trucks checking out the latest in Air Containers ~ can't hardly get that anywhere.
The best job is the one with entertaining and interesting stuff going on every day ~ even if the boss is bad.