For Origen, the spiritual life is life in the Holy Spirit. To be ‘spiritual’ then means nothing short of participation in the activity of the Holy Spirit. It means death and resurrection. And, this occurs primarily through prayer. As he says:

[David says] “to you, O God, have I lifted up my soul” (Ps. 25:1). For the eyes of the mind are lifted up from their preoccupation with earthly things and from their being filled with the impression of material things. And they are so exalted that they peer beyond the created order and arrive at the sheer contemplation of God and at conversing with Him reverently and suitably as He listens. How would things so great fail to profit those eyes that gaze at the glory of the Lord with unveiled face and that are being changed into His likeness from glory to glory (cf. 2 Cor. 3:18)? For then they partake of some divine and intelligible radiance. This is demonstrated by the verse “The light of your countenance, O Lord, has been signed upon us” (Ps. 4:6). And the soul is lifted up and following the Spirit is separated from the body. Not only does it follow the Spirit, it even comes to be in Him. This is demonstrated by the verse “To you have I lifted up my soul,” since it is by putting away its existence that the soul becomes spiritual, (Origen, “On Prayer,” in Origen, Classics of Western Spirituality, Rowan Greer, trans., NJ: Paulist Press, 1979, p. 99).