*Note this is written from the perspective of someone (Me!) who prefers GM based games as opposed to RPGs where the GM role is more fluid or indeed non-existent.*
So, you're going to be the GM. It might only be a one-shot game or it might a multi-year spanning campaign but what does that mean and how do you embrace this role?
Being the GM does not mean -
You're writing a story.
You're in charge.
You're there to entertain the players.
You're responsible for the game.
You do all the work.
Being the GM does mean -
You develop the initial concept / environment.
You adapt to how the others play.
You are a player too.
You encourage interaction between players and with non-player characters.
You will have more work to do than the others.
So why does this warrant being a principle? Simple really. Remembering that you are only 1 person in the play group who participating in the same game as everyone else is very key to ensuring that all the players (including the GM) round the table are having fun. To embrace the role you have to understand it and so do the other players.
This is especially key for those people who are GMs almost all of the time. To ensure that you are enjoying that experience and that the other players are sharing in the creation of the overall story you have to be mindful of the elements of this principle.