I've always found a fresh desktop wallpaper now and then is a good way to stop your PC feeling stale, and keeps me enthusiastic/more productive.
That said, I always have a hard time finding one when the time comes.
Unsplash seems like a good resource, but can feel so impersonal just having a nice picture of some mountains or a field. I have some friends who I know just rock whatever the default wallpaper for the OS is -- I can't verbalize why but something that feels tailored, or an image that brings me some joy, makes me much more comfortable using the computer.
Unfortunately the popular spots online I'm aware of for sharing wallpapers tend to lean toward certain subsets of interests (such as contemporary geek culture and/or lewd anime women) which you may or may not be into.
I've toyed with the idea of just having a solid colour to avoid any kind of decision fatigue, but it feels like staring at a wall - it's nice to have something with some depth behind all the flat windows.
Curious what others here on tildes use for their wallpaper, how often they change it, and where they might source a new one.