I’m a fan of doing things you’ve never done before. Not always, but on a regular basis. It’s a good spark generator for ideas and for work.
Paint with your non-dominant hand for an entire canvas. Use a drawing tool you’re unfamiliar with. Write some non-fiction. Play a different instrument, especially one you’ve NEVER held or messed with. Bake a dessert. Buy a book at random in the bookstore because the color is appealing, and start reading it.
Listen to minimalism, avant garde, or a tiny niche metal genre for an album or so and don’t do anything else until it’s finished. Paying attention to the unfamiliar can unlock new doors for you.