99 Bottles of OOP is a book by Sandi Metz and Katrina Owen that helped me feel like code could be good again no matter how bad it currently is. Website 
In the book, we're presented with 99 bottles of beer (or milk) on the wall. After a new requirement is introduced, we reworking the problem together while discussing how to improve the structure of code.
Each step is a line at a time such that our tests don't break, and then through a series of safe steps we rework the program into something that's open to our new requirement.
This book made me go and and read Refactoring Ruby Edition.