"In spite of our sinfulness, in spite of the darkness surrounding our souls, the Grace of the Holy Spirit, conferred by baptism in the name of the Father and the Son and the Holy Spirit, still shines in our hearts with the inextinguishable light of Christ.
… and when the sinners turns to the way of repentance the light smoothes away every trace of the sins committed, clothing the former sinner in the garments of incorruption, spun of the Grace of the Holy Spirit. It is acquisition of the Holy Spirit about which I have been speaking..."
St. Seraphim of Sarov, the Wonderworker
Spirituality in the Orthodox Church means the everyday activity of life in communion with God.
The term spirituality refers not merely to the activity of man's spirit alone, his mind, heart, and soul, but it refers as well to the whole of man's life as inspired and guided by the Spirit of God.
Every act of a Christian must be a spiritual act.
Everyday thought must be spiritual, every word, every deed, every activity of the body, every action of the person. This mean, that all that a person thinks, says and does must be inspired and guided by the Holy Spirit so that the will of God the Father might be accomplished as revealed and taught by Jesus Christ the Son of God.
whatever you do, do all to the glory of God. (1 Corinthians 10:31)
Doing all things to the glory of God is the meaning and substance of life for a human being. This "doing" is what Christian spirituality is about.
A person can abide in Christ, accomplish His commandments and be in communion with God the Father only by the presence and power of the Holy Spirit in his life.
Spiritual life is life in and by the Holy Spirit of God.
God's love has been poured into our hearts through the Holy Spirit which has been given to us. (…) …But if Christ is in you, although your bodies are dead because of sin, your spirits are alive because of righteousness.
(Romans 5:5, 8:1ff; Cf. 1 Corinthians 2,6, 12-14; Galatians 5).
It is the classical teaching of the Orthodox Church, made popular in recent times by Seraphim of Sarov (19th c) that the very essence of life itself, is the "acquisition of the Holy Spirit of God".
The new and abundant life given by God to man through Christ and the Holy Spirit in creation and redemption is the life of the Christian Church. One should not think of the spiritual life of the Church as some particularly special kind of "religious life" different from life itself as we have received it in our creation by God.
There are not "two lives", one "natural" and one "religious". There is only one life that is real, genuine and true. It is life with God, the life of the Church.
(From"The Orthodox Faith. vol. IV - Spirituality" by Father Thomas Hopko)
The essentials of Orthodox Spirituality are: Prayer and Repentance, Sacraments, Asceticism, Virtues