S. Anthony said that a man who knew he was praying was not praying. He meant that what was spontaneous and natural was most real; what was most studied and most conscious tended to lack reality.
Often I have heard people say they could pray to God while they were walking about and doing their chores, but that as soon as they knelt down they were plagued with distracting thoughts. The truth about that is that they prayed best when they were least conscious of themselves.
from The Life and letters of Fr Andrew, London, Mowbray, 1948, p210.