
John G. answered 08/09/19
Specialist in Research Projects, Story Continuity
Read books, watch television, eavesdrop on stranger's conversations. You'll notice that there a lot of different "voices" that people speak with - different pitches, cadences, and rhythms, and that's before you even get to word choice and sentence structure.
When writing a POV (any point of view, even one that you associate closely with), try to "get into character" as if you were an actor, so to speak. What are their goals with their next sentence or action? In this scene? In this chapter? In this story? Once you have that, make sure every action is building towards that goal. You'll find that, once you get all this squared away, you're going to start subconsciously writing a bit in that character's voice; embrace that. But also don't stress about it; get the whole story completed as a first draft.
Once the whole work is done, it's time to start editing, and this is where you can make these POV voices start to shine through. It's going to take a lot of time, but make sure you get a consistent voice throughout; don't worry about stereotypical voices: craft a voice for that character, and stick with it; your reader will get a feel for how that character talks, thinks, and acts. Consistency is key.