A medical certificate.
Today I got the specific diagnosis: I have contracted névrite vestibulaire virale (viral vestibular neuritis).
It is not a very serious illness, but it is a bit troublesome. This forces me to put the lifestyle rule of "never go to bed later than eleven o'clock; if things aren't finished, leave them for later" onto my schedule.
The time tonight that should have been spent working and writing was slept away. When I woke up, it was already past one in the morning. After finishing the lucky draw for the last medical certificate, I rushed over to write a new one.
I am giving away a copy of Grandma Ursula's Distracted, and after casually flipping through a few pages of this book once it arrived, it had me cackling with laughter.