How two sentences can take all day to write.

I have finally finished editing a short story for People's Friend.
I had a nice letter from them asking for just a couple of changes, which
sounded reasonable, I thought, 'I can do that', 'it shouldn't take long'
How wrong I was!
It was just a few small things, but changing one sentence changed the mood of the whole paragraph, then altering the paragraph meant altering something else on the previous page and so on.
I had to stop after several hours of deleting and writing and deleting, as I was on the verge of throwing my laptop out of the window.
Anyway, I have printed off the story ths morning and I'm off to the Post Office, with fingers firmly crossed.
If they don't like it this time, I may well cry. A lot.

Simple changes, there's no such thing is there?