Kristina Olsson is an Australian writer.
In an article for the Guardian newspaper she describes walking across England and discovering that long distance walking and writing a novel are similar things.
She makes the declaration ‘because the book has changed you’ – read the article, it is very good, and you will get the context.
Any artist must be changed by their art. It is a process. Words on a page, paint on a canvas, chisel against marble or stone. As you produce you also are produced.
Each keystroke or pen mark, each word, each description, each character voice, leaves a mark on you, a discernible indent which guides the next stroke/mark, and the next . . .
Whatever you write will change you. Recognise it. Embrace it. Use it in the next word and phrase. You will be a better writer for it.
Maybe even go for a walk.