zen in the art of archery

is an excellent book by Eugen Herrigel (isbn 978-0-14-019074-8). As usual I'm going to quote from a few pages:
He who has a hundred miles to walk should reckon ninety as half the journey.
I have also tried to keep my language as simple as possible. Not only because Zen teaches and advocates the greatest economy of expression, but because I have found that what I cannot say quite simply and without recourse to mystic jargon has not become sufficiently clear and concrete even to myself.
No reasonable person would expect a Zen adept to do more than hint at the experiences which have liberated and changed him, or to attempt to describe the unimaginable and ineffable 'Truth' by which he know lives.
I hit upon the thought that there must be a trick somewhere which the Master for some reason would not divulge, and I staked my ambition on its discovery.
In spite of its being divided into parts the entire process seemed like a living thing wholly contained in itself and not even remotely comparable to a gymnastic exercise, to which bits can be added to taken away without its meaning and character being thereby destroyed.
I once remarked that I was conscientiously making an effort to keep relaxed, he replied: 'That's just the trouble, you make an effort to think about it. Concentrate entirely on your breathing, as if you had nothing else to do.
A great Master, he replied, must also be a great teacher.
You had to suffer shipwreck though your own efforts before you were ready to seize the lifebelt he threw you.
Do you know why you cannot wait for the shot and why you get out of breath before it has come? The right shot at the right moment does not come because you do not let go of yourself. You do not wait for fulfilment, but brace yourself for failure.
Right presence of mind. This means that the mind or spirit is present everywhere, because it is nowhere attached to any particular place.
It is all so simple. You can learn from an ordinary bamboo leaf what ought to happen. It bends lower and lower under the weight of snow. Suddenly the snow slips to the ground without the leaf having stirred. Stay like that at the point of highest tension until the shot falls from you. So, indeed, it is: when the tension is fulfilled, the shot must fall, it must fall from the archer like snow from a bamboo leaf, before he even thinks it.
If I tried to give you a clue at the cost of your own experience, I should be the worst of teachers and deserve to be sacked! So let's stop talking about it and go on practising.
Don't ask, practice!