If you practice mediation, any religion or organizational strategy, your goal is to be Mind Like Water.
The goal is to achieve a level of calmness and peace that empties your mind. This empty mind is then ready to handle anything life throws at it.
In Getting Things Done, the goal is to build a trusted system that can track everything so your mind doesn't have to. Why is this important? Our mind mistakenly believes that everything it is tracking has the same immediately critical importance. By externalizing all of these elements into a trusted system your mind knows is reliable, you offload all of this mental energy consuming tracking and allow yourself to consciously set the appropriate level of importance for each task. If an urgent surprise does occur, you have the mental clarity needed to calmly analyze it and decide intelligently how to handle it. You don't panic and over/under react.
In Taoism, there is a core belief in something called Wu Wei. Translated it means Action of non-action. It is used to describe a state of being where you are calm, in control and in a state of clear. A state in which you are automatically aligned with the flows of nature, in a way where you respond perfectly and appropriately to every situation.
The most easy to understand description I have seen for "mind like water" comes from Karate and is repeated by David Allen when explaining GTD.If you throw a pebble into a still pond how does the water respond? It responds totally appropriately to the force and mass of the pebble then quickly return to a state of calm stillness. It doesn't over-react or under react. It reacts perfectly.
The greatest sports players use this powerful mental tool. They practice so much that when they finally compete, everything is done automatically without really thinking about it. This means they are more in tune to reality and are able to respond to changing situations faster and more appropriately.
Your goal in life is to live "Mind like water". This means using a trusted task management system to free your mind of the mundane so it can concentrate on being spectacular. Practice meditation or religion to learn calmness and stillness. Learn to live with a silent mind (much more difficult than you can imagine). Once you achieve this goal, everything in your life will seem easy and effortless. Good things will flow to you and bad things will naturally repel. Things that seems like unsurmountable boulders turn into small pebbles.
Learn from water. Be Like water.