When we pray, God does not only ask from us to be vigilant over our body but also to watch over prayer.
Once you will see that evil thoughts spread in your mind, throw amidst them the name of Jesus and they will be scattered as the smoke in the sky.
As long as we call the name of Jesus, our heart will become a spring of life, and if we cease to call His name it will become a spring of death because then only evil things will come out of it. When we pray, God does not only ask from us to be vigilant over our body but also to watch over prayer.
(Translation from Arhimandrit Cleopa Ilie, Îndrumări duhovniceşti pentru vremelnicie şi veşnicie, Editura Teognost, Cluj-Napoca, 2004, p. 119)