An elderly nun who went to confession to a famous elder in Optina Monastery in Russia during the last century. She asked him to be her 'spiritual father' and he agreed. She then asked him for a 'prayer-rule' and he complied by asking her to go back to her cell in the convent and say ONE OUR FATHER in her Holy Corner each day WITHOUT DISCRACTION ... and then to return and report to him her progress the next week.
She was insulted ... and said to the elder, "I'm a nun for many years Batiushka ... and I have come to you to make spiritual progress and yet you give me only ONE OUR FATHER for my prayer-rule?" And the elder reminded her that HE had now agreed to be her spiritual-father and so she needed to do EXACTLY as he asked her. So she went home to the convent ... and began her new 'prayer-rule' ... and lo and behold 'warfare'! When she returned one week later ... the elder asked her how she did ... and she wept and admitted that she could not say even ONE Our Father without distraction.
So then elder then said to her, "Now suppose that I had given you a longer prayer-rule ... how in heaven's name would you have ever completed that?" Then he taught her how to correct her thought and become attentive and how to place herself in God's presence and say ONE PRAYER with attention.