Merlin Mann hits gold
"If you allow the world to decide how you feel, you are fundamentally screwed. Because you're never going to win. That's not a fair fight. There is way more world than you."
If you can't win, perhaps you shouldn't play at that game
Think about this for a second. There is almost no way you will ever be able to win or even just draw if you allow other people (the world) to determine what you feel, especially what you feel and how you think about yourself. So perhaps you should not play at that game. However, often that's easier said than done.
Sense of self required
If you have no clear sense of "self", no real set of clearly determined goals that are relevant to you as well as a method, a way to work towards the completion of these goals and the development of others, you will become very reactive. In being reactive, you will allow others to influence the way you feel about you. That's your self-image.
As an example: Are you determined by what appears in your inbox, or do you determined whether you check your inbox and what you will or will not do with it? How does that influence how you feel about how "accomplished" you are? How well you are on top of your tasks?
GTD as a tool(set)
So, how does GTD come into all of this?
GTD is, to me, a specific set of activities which allow you to determine what you are about, allow you to translate that vision in a strategy, link this strategy to objectives and execute on a daily basis towards these objectives in an organized manner with minimal/optimal tool set changes. That's 50.000 ft to runway for the in-crowd.
In other words, your proper application of GTD should result in a better sense of self which in turn should protect you from the onslaughts of the world's (very temporary) onslaught on you. Very temporary because if you really believe that other people think about you that much, other than your loved ones, you need to think again.
And after all, isn't that one of the things that "Mind Like Water" in GTD parlance is all about?