MMA champion and Karate master Lyoto Machida uses meditation techniques before fights to attain mushin, a concept that, by his description, is in all respects equal to flow.
The last time I consciously practiced the blend of external environment and my mind was when I was playing tennis. My aspiration was to become “ONE” with the turf that I am playing on, relaxing my breathing and absorbing the ball and its reactions as those as if they were the part of my being; I’d try to make the ball a part of my mind.
But also learning some martial arts made me realize how these two can converge. Just in this case you would try to feel the opponent, as a part of yourself, and then you would be in a better position to predict their moves and act accordingly. Bruce Lee would call that:
Mind like water.
When it comes down to knowledge work, the same philosophy can apply. My mind aspires to make you (my reader) and your reading experience, a part of my mental state. This way my mind can shape your mental experience, and my aim is to do so through words, in such a way that reading my words inspires you to a higher mental state, so that you can get more done.
This is why I am so hung up on working out and eating clean (even though I am not following it up religiously, as I want to). Because there is an obvious link between mind, external reality and actions that deliver results. Our belief and paradigm are the ultimate determinant of what is happening in our lives, and how we grow.
Feeling in tune with your body through fitness is empowering certain areas of your brain that are connected with higher mental states. Being a “mental warrior” of 21st century has good body as a foundation of productivity. You need to take care of your own body, so it can take care of you.