Then of course the other 20% of the stress are your reports actively trying to undermine you, or publicly question your purpose/existence, or cut you out of decision making processes, going behind your back and contradicting previous agreements, trying to short-circuit or subvert agreed processes etc etc for above childish reasons.
Turns out that a lot of "professionals" are not professional at all and are actually pretty petty, spiteful, grudge-holding argumentative children who go into a strop (or as the article puts it "go lay on the grass thinking about their project") for a day or 5 if they don't get their way.
The rest of being a manager is a breeze though! 10/10 would buy again etc :)