Write what you know. But don’t take that too literally. Maybe you don’t know what it feels like to be shot or wounded. Do as actors do: think back to a situation of pain that you did experience. I always remember Meg Ryan saying in an interview, about playing a soldier, that she felt back to the worst pain she’d ever known: childbirth.
In My Left Foot, Daniel Day-Lewis played the severely paralyzed Christy Brown. Famously, offscreen, he refused to break character and had to be wheeled around the set in his wheelchair, so that he might, literally, experience life as Christy Brown. He broke two ribs during filming from being hunched-over in his wheelchair for so many weeks (to the irritable curses of the film crew, who had to lift him over camera and lighting wires.)
An actor has to be the character. As a writer, you have to create or re-create the character on the page, with words. You have to know what that person is thinking and above all feeling. You need to go there and feel into it. It might be painful. But – and this is part of the alchemy of writing – if you do get to be the character and feel the emotion, it somehow charges the writing. You won’t need to be flowery and longwinded in a desperate bid to describe that emotion.
One of the most common reasons stories and novels ‘don’t work’ is because the emotional plotline of the characters is not fully developed, and their emotions not fully rendered.
And they won’t be unless you, who created the characters, get in there and feel the feelings.