This was not at all what I was expecting from the title. I thought I was going to read an article about the importance of taking one day a week to not write any code. I'm sure that between startups, work, side projects, etc. some of us are coding every day on something or other.
As someone who often works alone, one of the best things I've done is to find someone else to share code, problems, and ideas with on a regular basis, even though we're not working on the same projects. It's helped me grow as a developer, has improved my mood, and has also just been an enjoyable.
But I still really do think it is important to make sure there's one day a week where you don't touch anything related to work or code.