According to some researchers downtime allows your brain to evaluate your experiences in ways that could help you improve your self and your work. But true downtime requires you to cut off the flow of information.
So, no phone.
If you need more motivation, why not help children in need get clean water for every ten minutes you go without your phone?
Still with me? Feelin' good about helping the needy and taking care of your brain at the same time?
Good. Now we need new experiences.
Anytime you encounter something new, it can actually "spark different synapses in the brain," which you need for creativity and, of course, for all kinds of writing.
So, if you can't take a micro-adventure like camping in your backyard, try taking a written micro-adventure.
You could draw a map of the first neighborhood you can remember living in.
This is a great way to explore a place you've already been, blending downtime with new experiences and potentially maximizing brain gains. You'll be surprised by how much you remember or, in my case, by the massive blank spots.
Draw a map of an imaginary continent.
Where are the points of interest, and what are their names? What's the climate like here or there? Who knows, you may be on the verge of writing a fantasy novel when you're done.
Mapmaking not your taste? In a few sentences, describe an imaginary setting that you'd love to explore.
Inventing an environment is another good way to get some downtime and new experiences all at once. You can mosey around in an imaginary comfort zone while still conjuring up new sights, sounds, and smells to trigger those synapses.
Did the electric sandstorms in the new Mad Max pique your interest, or do you prefer the arctic climes beyond the Wall in Game of Thrones? Take that inspiration and make something new.
Instead of limiting your travels to the real world or even other writers' fictional worlds, try inventing your own setting. Load it with adjectives, and don't worry about sharing it. This is your world. Claim it.