"I experienced doubt long before I met Dean and you. It's not pleasant. It feels like a sickness that eats away at you. Angels aren't designed for it..."

And yet he knows the doubt is good. Anna has doubted, he has doubted, and it led them on better paths, fighting for what they believed in respectively. He still didn't look forward to doubting more now.

"Yes, Sam."

It's easy to follow these orders at least, to lean against the wall for Sam in order to continue this exercise in humility.