It helped me by keeping the image of reacting to outside interuptions with just the right amount of energy and remembering to return to that original state. It's kind of zen, but practicing on how I controlled my reactions and keeping my work schedule flexible with GTD helped alleviate a lot of irritation, anger and stress in my work life.
Even when I have the CEO on the phone needing me to fix her laptop, the prepress manager needing new press-ready art on my IM and my assistant pestering me if she can have friday off and they all hit me all at once I know I can get back to that original state and that my work will get done.
Don't fret, it takes a LOT of practice. Some days I fall off the wagon and get frustrated, but it gets easier.