Writing your world up is one thing. You can take notes, document everything, draw up timelines, and so forth. That’s a matter of technique, imagination and, frankly, your ability to write everything down. Getting yourself to use all those notes? That’s another challenge.
How do you actually bring all this worldbuilding to life? How do you get the details to live and not sit forgotten on pieces of paper, wikis, and documents? How do you keep this information in mind? How do you avoid breaking your own carefully-crafted continuity without turning every bit of writing into a chore of review?
Perspective is my answer, though that now deserves an explanation.