Working on 3-d visualization is like a muscle. You start small, colors, sound, humanoid shapes, emotions. Then you work your way up, textures, shade(in books you usually have omnipresent vision it is difficult to forget about the elephant in the scene after you read about it), heat, pain.
Every time you ‘render’ a new piece of information,you contribute to your edification, like minuscule Legos creating a robust stronghold.
Mental fatigue applies as well, some days you have a lot of fuel, ready to stoke the fires of your imagination,on others nothing will even get a gentle chirp out the old hamster.
Like all things in life, practice.