I've spent the last few months - a pace upon which the client and I agreed - professionally critiquing a manuscript. (See my writing and editing business.) I finished my final review this evening.
I'm pleased the work is done, for now I can (until the next job comes, that is) focus on my own manuscript edits. But I'm also sad to see it end, because assisting another writer with their work proved envigorating for me. I loved throwing myself into their manuscript, playing a professional role in figuring out how to make the story better and, maybe most importantly, building a rapport and gaining a friend.
I hope to do it again soon.