I want to increase my imagination. how can this be done?

im a writer / animator i use my imagination allot in my work. so much that nowadays visual imagery doesn't come to me the way it used to i.e like when i was a child. i postulate that the seratonine or dopamine or whatever that is responsible for that part of the brain, doesn't work that much because i use my imagination allot. sort of like what happens to crank addicts that have burned out the pleasure center part of their brain. i know it still works but not like it used to. i was wondering if there was something i could do about it.