What is it that commends our own life? Is it miracles, or is it a life scrupulously and uprightly lived? It is rather from the latter that miracles arise, and to that they tend. For he that lives a worthy life, draws this grace upon himself; and whosoever receives such graces receives them that he may help others to amend their lives. For even Christ wrought miracles that He might the more be accepted as worthy of belief, and so might the more attract men to Himself, and by this means bring sanctity into their lives.
The more wood you pile on a fire the more heat you get, and thus it is with God - the more you think on Him the more you are fired with love and fervor towards Him. He who loves the Lord is always mindful of Him, and remembrance of God begets prayer.