Everybody does at some point.
Unseen. Unnoticed. Unappreciated.
Don't let it get to you. It's a poison. A darkness thick as molasses that will suck you under.
Do the work instead. Yes, even if you're in pain. Especially if you're in pain.
Pain is only weakness leaving the body.
Getting stuff done is better, healthier.
(illo by Paul Pope. A guy who gets a lot of stuff done in a lot of different venues)