Have you ever gotten up in the morning and just knew that it was going to be one of those days?  You aren’t upset about anything.  You aren’t in pain.  You have nothing in front of you that is vexing you, or causing you concern.

You just know that everything you do that day is going to feel like you are trudging through mud.

Not a depression.  Just a struggle.

If you work as part of a team, you just know that this is a day to work on an independent project.  If you work on your own, you just know that today is a day to close your door to keep folks at bay.  Because the bane of your existence today are these types:

And you just know you will want to express to them just exactly where they should put all that sunshine.