> It’s no good nursing your private resentments for years, while telling your boss once a week that everything’s fine, and then suddenly walking out on them. Strongly disagree with this point. Your departure should be an enormous shock to management, otherwise you've just spent weeks or months mouthing off about work to them, they've not fixed anything and indeed might even have lined up your replacement already.
> Instead, you should make sure that if you’re unhappy about something, your boss knows it pretty much as soon as you do.
Keeping a paper trail of those discussions also help even if it's just for sanity check for your future self.
Chances are most people won't help you because most people are bystanders or cowards in those situations (anecdotal, maybe everyone I know and I are unlucky).