St. Diadochus of Photiki: On Baptism and the Remembrance of God

 Before holy baptism grace encourages the soul towards good from the outside, while Satan lurks in its depths, trying to block all the intellect's ways of approach to the divine. But from the moment that we are reborn through Baptism, the demon is outside, grace is within...

It is a mark of one who truly loves holiness that he continually burns up what is worldly in his heart through practicing the remembrance of God, so that little by little evil is consumed in the fire of this remembrance and his soul completely recovers its natural brilliance with still greater glory.

+St. Diadochus of Photiki, from One Hundred Texts on Spiritual Knowledge and Discernment, The Philokalia, Volume 1

St. Seraphim (Sobolev): On saving zeal

 The Grace of God only acts in us, renews us, and saves us, when, on our part, saving zeal is brought to light, without which the Grace-filled fire does not become inflamed within us nor act in us with its revivifying force. After all, the Grace-filled fire was as present in the foolish virgins as it was in the wise ones. But the former, instead of zeal, had a lackadaisical attitude, and the fir of their oil lamps went out, and along with it they were deprives of an inheritance in the Heavenly Kingdom of Christ. (cf. Matt 25:1-13) For this reason, the Apostle Paul, in his First Epistle to Saint Timothy, warns us against a lackadaisical attitude when he says, "Neglect not the gift that is in thee, which was given thee by prophecy, with the laying on of the hands of the presbytery." (1 Tim 4:14).

+St. Seraphim (Sobolev), from St. Seraphim of Sofia, His Life, Teachings, Miracles, and Glorification. Part II, The Archpastoral Ideal

Fr. Michael Shanbour: Understanding God's Grace

 If we desire to feel the warmth of the sun, we must make the physical effort to walk outdoors and expose our skin to its rays, perhaps shedding some of our clothing. After being tanned by the sun’s rays, we would claim not that our tan came about as the result of our own power, but rather that we desired it and put ourselves in a position to receive it. 

And if there are clouds covering the sun, we do not say, “The sun is angry With me.” The sun has not changed in any way, nor have the sun’s rays ceased to shine. Rather, we acknowledge that the clouds are obstructing the sun’s light and power, keeping it from having its natural impact.

The same is true in the spiritual life. If we desire to be in the presence of the spiritual Sun, we Will adopt a Way of life that naturally exposes us to the rays of God’s grace. This is the way of love or of keeping the commandments of God - “If you love Me, keep My commandments” (John 14:15). It will not be our effort, our works, that save us, but the grace of God, which brings us into union and communion with Him.

+Fr. Michael Shanbour, from Know the Faith: A Handbook for Orthodox Christians and Inquirers, Chapter 2, Grace