Enjoy the challenge of diplomacy. It's the subtle dark art of telling somebody to go fuck themselves in a way that they not only do it, they thank you for your kind suggestion and think 'What a lovely person!'.
More seriously, it can be very freeing, as you don't have to worry about upsetting anybody but can absolutely state and maintain your boundaries by following the framework.
No more agreeing to things whilst silently seething; you've politely stated that you would be delighted to assist, but you are required by Statute to submit x return by five working days after y event and you would therefore need z days before you were in a position to do so. Otherwise known as 'No, I am not sat here filing my nails and drinking coffee whilst looking pretty whilst you run around doing all the work. I will help because those envelopes should have been stuffed seven days ago, but I am not ignoring a legal requirement that could get us in a whole boatload of shite in favour of digging you out of a hole'.
Or when there's a snotty email cc'd to management ordering you to include Person A in an email group for notifications, you politely respond with a 'Thank you for the suggestion - IT is already included in the notification, but I will add Fred Bloggs' individual email to the group in future'. Otherwise known as 'Look at the bloody To box where it shows that they've been included and have already replied on this thread, you flaming muppet'.
And then you get to come online in your free time and swear and vent as much as you like about other things. It's all rather pleasing, really.