The finale of the Christmas season is not Christmas day or even Epiphany but the Baptism of Jesus. This is more emphasized in the Eastern Church. Christmas is Trinitarian. It is to the Father, through the Son, and in the Spirit. Christmas is focused on Christ and culminates in the Holy Spirit, the only true Christmas Spirit. Thus, we should be looking to conclude the Christmas season by having the Holy Spirit stirred into flame in our lives (see 2 Tm 1:6-7). In a way, the Christmas season ends as Easter does with a new Pentecost.
In our Baptism, Jesus has immersed us in the Holy Spirit (see Jn 1:33). We should be preoccupied with the Holy Spirit. However, we can fall into the temptation of being preoccupied with ourselves. The Lord teaches through the Church: The more we renounce ourselves, the more we walk by the Spirit (Catechism, 736). The Spirit poured out within us fights against our selfishness (Gal 5:17). By the Spirit, we can put to death the evil deeds of the body (Rm 8:13).
In these last nine days of the Christmas season, let us not merely have the Christmas spirit but may the Holy Spirit of Christmas have us. Then we will truly have a great Christmas.