So, I know I don't post much on this board, but that doesn't mean I'm not writing and trying stuff; and one of the ideas I've been working on recently has been a real help to me as a writer when it comes to POV, which is why I thought I'd recommend this as an exercise to everyone.
Essentially, it's just a multiple first person POV narrative. But, of course, this is kind of weird, since normally first person only has one narrator (because, well, obviously). When you have multiple (in my case, two) first person narrators, however, it makes you think about things differently. All of the sudden, you've got something completely new to balance.
See, when people write in first person, it's not uncommon to see the character's narration drift into the writer's own style of writing. Makes sense, that's the voice the writer is most comfortable in, but the problem is that it doesn't suit the character. In third person POV (especially omniscient), the author's voice is tantamount, so it can be whatever it wants. Whatever the author is comfortable with, that's the voice. However, in first person POV, the voice is of the character. And a lot of times, I feel like writers forget that. They forget that in first person POV, it isn't about their own personal voice, but about the voice of the character they're writing.
That's where this exercise comes in. If you create even two first person narratives that you switch between at regular intervals, you get a unique problem as a writer. Your standard voice won't work anymore. Not because there's necessarily something wrong with that voice, but because you simply can't feasibly use the same voice for two characters. And since first person POV is all about the characters, that creates an issue.
How to solve that issue? The writer has to learn to write both voices differently, so as to effectively distinguish them. The reader should know, just by reading the voice, which character is speaking. Even if the POV switches, the audience is aware of it instantly, because of the difference in the delivery of the narration as it relates to the character at hand.
For example, one character could be calm and verbose, while the other is neurotic and uses choppy sentences. Doing a writing exercise like this allows the writer to practice really getting into the mindset of the character, writing as though they were him or her. Even better, you learn how to better control your own voice in the process.
So yeah, multiple first person POVs. Pretty good exercise. Totally recommended.