It's what God gives us that is important in attaining perfection – Not what we give Him. He gives us mercy. He gives us forgiveness. He gives us His love. At the moment of our Baptism we are pure. At the moment of absolution in our Confession we are pure, at the moment we receive Him into our body in Holy Communion we are pure. Not as the result of our efforts but as His gift of mercy and love. We then continue to struggle against the evil forces of the world and can be tempted to forget and fall into error anytime. God is still there with mercy, forgiveness and Love. Out of our love for Him we are sorry for our forgetfulness and error and seek His forgiveness and mercy which He freely gives back. We struggle to improve so we will not be as forgetful. We fast to help us remember Him and to increase our control over the passions of the Body. We pray and learn to have the Jesus Prayer on our lips when we are tempted or face difficulty. We work to improve ourselves to be a good servant of our Lord. We do not do this for merit but out of our love of Him, our desire to do what He wills recognizing our weaknesses when facing the spirutual war we are engaged in. This is an ongoing process of growth. It is what we call the Orthodox way of life. It is a life of repentance.
The nature of the difficulties we face are highlighted in St. Paul's Letter to the Ephesians 6:10-17
"Brethren, be strong in the Lord and in the strength of his might. Put on the whole armor of God, that you may be able to stand against the wiles of the devil. For we are not contending against flesh and blood, but against the principalities, against the powers, against the world rulers of this present darkness, against the spiritual hosts of wickedness in the heavenly places. Therefore take the whole armor of God, that you may be able to withstand in the evil day, and having done all, to stand. Stand, therefore, having girded your loins with truth, and having put on the breastplate of righteousness, and having shod your feet with the equipment of the gospel of peace; besides all these, taking the shield of faith, with which you can quench all the flaming darts of the evil one. And take the helmet of salvation, and the sword of the Spirit, which is the word of God."
What many Protestants see as working for merits are the things Orthodox Christians have done since the time of he Apostles to be good sons, to hallow His name, to live a more virtuous life according to His commandments. We need His grace to do so and we also need to put all our own energies into following what God desires for us. It is living this kind of humble life in eyes of God that we become justified so that at the time of the final judgement when the actions of our life will be examined in detail and truth we will be accepted into His Kingdom. Without these "works", without our own efforts, we will not improve our ability to serve our Lord as his son or to glorify Him as He intended. It's wrong to think of these efforts as earning merits. Orthodox Christians do not have this idea of merits tied to our personal efforts because we have a sacramental life as the foundation of out faith. We have much more than a book to guide us. We know God will help us and we know that we are weak needing his help. We also know we have free will and a body full of passions, that we live in a world controlled by evil forces that we must struggle against. We continually "Lord have mercy on me." we continually seek His grace and participate in His sacraments where we are give the gifts of His healing and grace. It is a complete way of Life in Christ.