What it has to do with GTD
Well how do you decide what to do, I mean the MOST IMPORTANT things to do right now?
How I decide and create this priority list is by imagining that I am not going to wake up tommorow, or I won't be here in two weeks, two months, two years etc.
So you wanna know your MUST DO's and set your goals for different time frames- thats how you do it.
You want to get things done, REALLY IMPORTANT things, then thats the most simple, powerful and exact way I can fathom of doing it.
If you want to give yourself excuses to keep doing the things you dont want to do, keep putting off the changes your afraid to make then by all means don't even think about the fact that one day you will say goodbye to all of this, every person you love, one unplanned day it will all end for you.
How can a person possibly manage their time if they can't even see that it has a beginning and it has an end. Plan for 5 years, you might not make 5 years! You might make 50 more who knows!! Who cares, all you'll ever have is one big long now.