I just finished teaching a class of about 50 maintenance people some of the nuances of water heater repair, and in the process, I learned something about my source of strength.
We were playing with some dead water heaters that had been captured on their way to the dump. I like using old heaters as a teaching tool; they have stories to tell about their lives, if you know how to look. In that looking, we were removing pipe nipples from the tops of the heaters — and some were rather stuck.