> Also, some of my colleagues (who'd been working for decades, just like me) seem to still love it and thrive on the stuff that made me want to quit and demotivated me. I'm fascinated with how some people like them are able to persevere and thrive in the same situations that make people like me quit and burn out.
It really comes down to the level of influence and control you have in the organization.
If you feel empowered to enact positive change, even if it's just at your level in collaboration with your colleagues, then that can be enough to remain motivated. Speaking for myself, for years, this describes how I managed to stay motivated through a lot of BS.
But when that falls away--when senior management becomes ineffective, when your colleagues leave or become demotivated themselves, when leadership starts to get in the way of your enacting change, when the organization becomes large enough that it's more likely to resist change than embrace it--that is when management becomes, at best, an unrelenting chore.
I've been a middle manager for nearly eight years. The first 5-6 of that were pretty good. But in the intervening years the company has grown and is now big enough that my ability to enact change in the organization has all but disappeared and I'm considering my options.