The Flow:  The Psychology of Optimal Golf Performance concept developed by Mihaly Csikszentmihalyi

Have you ever felt 'in the flow' on a golf course before?  It is the feeling that you control every facet of the game.  You already know putts are going to go in and you can almost see the path illuminated along the line to the hole.  It is a 'no fear' zone; you can't even conceive that anything can go wrong - those types of thoughts just stop being generated by your brain. Your attention is heightened, your focus narrow and external.  There is a sense of calm and peace inside you.

These are some of the most extraordinary moments in life.  Now, science is not only able to explain them, but can now teach you how to trigger them.  You can achieve flow much more often, with some understanding of how it works, and lots of mental training and practice.

One music composer describes being in the flow as the following: 'You are in an ecstatic state to such a point that you feel as though you almost don't exist.  I have experienced this time and again.  My hand seems devoid of myself, and I have nothing to do with what is happening.  I just sit there watching it in a state of awe and wonderment.  And the [performance] just flows out of itself...'
You will, by far, play your best golf when in this state.  But it takes practice, just like your golf swing takes practice.  The muscles, in this case the brain, need to be trained and conditioned.

The experience of the "zone" ... ecstatic state described as "witnessing" by Vedic seers. It's a characteristic of the transcendent reality of pure consciousness, which is an absolute, unbounded field. This state is cultured in meditation and its establishment in the mind along with waking, dreaming and sleeping is the first stage of "enlightenment".

The following video on flow presents the concept and how to more easily achieve it.