I decry "was" an evil word, to be avoided where possible!
He was sitting - weaker
He sat - stronger
We've had this conversation before, though.
Ooh, Brian! We'll have to agree to disagree. Yes, hunt for "was"s, but not all "was"s are bad.
There's a time and a place for progressive tense; it can alter a sentence's meaning just so, or fit better with the flow of a line. I wouldn't use it everywhere, but sometimes...