Intention.
Nothing much happens without intention. Creation ceases. The driving force is lost.
Our entire lives are directed by our intention; our jobs, interests, hopes, romantic inclinations, relationships, ambitions, aspirations, thoughts, desires, … in fact anything we want to achieve.
As Deepak Chopra said, “Everything that happens in the Universe starts with intention”.
I suspect that you cannot perform even the smallest of acts without it, unless they are ‘fight and flight’ actions triggered by the Sympathetic nervous system…by the reptilian brain. This must mean that a lobotomy is only partial loss of intention (you can perform a great many actions having had one … apparently).
Unintended outcomes.
I know that all of us at some point have said, “I didn’t mean to do that!”, but perhaps we really mean, “I didn’t intend that outcome”.
And there are also degrees of intention. How much do you want to achieve something? Massively? Or would it just be nice if it happened, i.e. no real intention? Or somewhere in between?
How does this relate to tai chi and qigong?
Both tai chi and qigong are to do with understanding the process of constant change (in life), and with creating change (in one’s own life). By understanding change and by working with it so that change works in a constructive way for you is (to be a bit 60s about it) ‘going with the flow’.
Both taiji ang qigong are driven by intention.
If you want energy to move through the body, if you want to create change, you need the intention to do so.
In tai chi and qigong, you learn to coordinate the body so as to make changes as efficiently and effortlessly as possible, so that it feels physically easy, and as though only the thought produced the result.
When you move in this way, you know without question that your tai chi or qigong movement was correct, that every cog in the mechanism was well oiled and functioning perfectly, … that you got it ‘right’.
Observing.
Without intention we are sitting in life’s armchair watching the show; we are observers. This is not to say that this is a bad thing, far from it, because in both tai chi and qigong you not 
only need intention, you also need to be an observer – but simultaneously.
You provide yourself with a plan (the intention), and then, because you are so familiar with the movements, you observe yourself achieving it, and move into the feeling. And yes, plans can change, but this is adaptability, and relates more to 2-person taiji rather than solo work.
All of us are more relaxed when we know where we are going both physically and metaphorically.
Once you have the plan, you can enjoy the journey there.
Tai chi and qigong classes with James Drewe at http://www.taiji.co.uk/classes.
Taiji & Qigong (classes with James Drewe) 