A great quote from John Chrysostom on prayer:
Prayer is the fortress of the faithful, prayer is our invincible weapon, prayer is the cleansing of our souls, prayer is the ransom for our sins, prayer is the foundation and source of countless blessings. For prayer is nothing more than conversation with God and association with the Master of all. What could be more blessed than a man who is deemed worthy of constant association with the Master?
— St. John Chrysostom, Baptismal Instruction, p 115.