There doesn't have to be a reason

I woke up exhausted and cranky.
I felt lonely and isolated.
The sadness and pain all came back with the revitalized memory of they see this as something I'm doing to them instead of as something that's happening to me.
I am reminded that my brain doesn't work as it was designed to, but I'm supposed to keep up regardless.
I can't think, I can't focus, I can't remember, I can't get any work done.
How can I be this tired?

I wept from the time I poured my coffee, then all the way to work, until I stood in front of the parking garage elevator.

I can't really say why.