I work on a side project that's designed to improve the projects we work on.
I strongly believe everyone (literally everyone, including support and admin staff) should have side projects that are aligned with the future goals of the business they work in. It doesn't need to be code; it could be developing better processes to improve the way things are done, to document everything, to automate away boring things, to test other people's projects, to just learn something useful, whatever. If you have a side project then you're never left doing nothing and you have a sense of being a more integral part of the company culture.