Being responsible for the entire scheduling and organisation of 3 people, at least one of whom (the 15 year old) actively resents it, but can't seem to manage to do for it himself.
Example:
In July my mum gets in touch and asks if the DC want to visit (we're estranged, but I don't want to prevent the DC from seeing their grandparents if they want):
I ask the DC if they would like to go and visit Grandma and Grandad. They say yes, but after various messages back and forth we realise it can't be the summer holidays, it has to be half term. More messages, taking into consideration DS2 wants to be back for trick or treating here, we establish a time frame, I buy train tickets (which I have to schedule time to physically collect). More messages and discussion to establish exactly where in the busy station the DC will meet my DP. Remembering it's going to be DM's birthday, so getting the DC to choose her a present. Remembering to sort out DS2'S Halloween outfit and buy a pumpkin before they go, so it's ready for him to carve when they get back on Friday. Overseeing them packing (actually I haven't literally demanded to see every thing DS2 is putting in his bag, I have just asked him to tell me, which I know is a mistake but fuck it). Getting them to choose some snacks for the journey and remembering to have everything in for their sandwiches. Getting them to wrap Grandma's present.
None of this would they take the initiative to do themselves, even though DS1 is nearly 16. And now he's just had a go at me because he never gets to do anything with his mates (because he's useless at scheduling mainly, as are they), and it's all my fault because I made him go to Grandma's at half term, and actually he said he didn't want to go (he fucking didn't).
Now I've run out of energy to organise my own shit, because I've been so busy organising everybody else's.