The brethren asked Abba Agathon, "Amongst all our different activities, Father, which is the virtue that requires the greatest effort?"

He answered, "Forgive me, but I think there is no labor greater than praying to God. For every time a man wants to pray, his enemies, the demons, try to prevent him; for they know that nothing obstructs them so much as prayer to God. In everything else that a man undertakes, if he perseveres, he will attain rest. But in order to pray, a man must struggle to his last breath."