This is good for flexibility. Could be a poem, or a nonfiction article, or a letter to someone. Or a scene that’s light and funny if you’re usually inclined to dark material. Or a thoughtful, honest Yelp review of a restaurant. I keep a file in which I describe and review perfumes I’ve tried, which is mainly for my own practical reference, but also can count as a writing exercise since it demands that I pay attention to the way something smells and put the impression into words.
As with your free-write journal, this doesn’t necessarily have to be anything you share with anyone else. Goodness knows the poems I’ve tried writing are not ready for prime time. (Poetry is decidedly outside my wheelhouse.) But it’s another form of writing practice and is thus good for the creative mind. Then you’ll be feeling more ready to get back to your fiction!