I don't know how we do it, either.
The trick (perhaps) is not to think about the big picture, but to just plow forward with the details.
I read each word that goes into Genii three times: first when the story or column comes in. Second when I edit it, and third when I proofread the entire issue after it's laid out just before going to the printer.
In my spare time I watch horror movies, The Big Bang Theory (for reasons that will become evident after you read the November/December issue), and ... yes, I'm writing several books at the same time. Was thinking of taking up knitting, too.