As one of the regular contributors on the Volleyball board likes to say:
"It's only easy if you don't want to do it right!"
Volleyball is definitely not physically demanding, but it is just as mentally demanding as any other sport I have worked. I have been a HS
VB official for 20+ years and it is "easy" for me, just as it became easier the longer I was a basketball official, softball umpire, etc.
I will say that
VB is the one sport it took me the longest to become comfortable and confident in my ability as an official.