St. Theophan the Recluse: Begin each day as if it were the first

 First of all, do not ever think that you have already succeeded in doing something. Our weakness is that when some tiny good shows itself inside of us, we immediately cry out, "There, I've done it!" Drive out such thoughts. For good never comes easily and all at once as the adversary suggests. If you yield to this suggestion, you energy will immediately weaken, and then discord will be close again. So that you do not fall under this evil thought, each day, when you get up, put yourself in such a frame of mind as if you were beginning to labor on this path for the first time.

+St. Theophan the Recluse, from The Spiritual Life and how to be Attuned to It, #44 Warnings to one on the True Path