Once, his disciples asked Abba Agathon, "Among all good works, which is the virtue that requires the greatest effort?"
Abba Agathon answered, "I think there is no labor greater than that of prayer to God. For every time we want to pray, our enemies, the demons, want to prevent us, for they know that it is only by turning us from prayer that they can hinder our journey. Whatever good work a person undertakes, if they persevere in it, they will attain rest. But prayer is warfare to the last breath."