I'd assign having to come home from vacation. Even with a sprained foot. (And boy, am I grateful I didn't react to the flu shot I had three days before we left.
)
On a corollary, I would also assign having to go in for a cholesterol blood draw three days after said vacation. The draw itself is bad enough (one of those things they always want to do at the crack of dawn), but with it coming three days after a lot of meals that were not the usual diet, I just know things will be out of whack.