Life in Christ is like a race (see 2 Tm 4:7). We must hold out to the end and cross the finish line (Phil 3:14) in order to win (1 Cor 9:24). If we hold out till the end, we will not only escape the second death but also bear a great harvest for God's kingdom (Lk 8:15) and receive the crown of everlasting life (see 2 Tm 4:8).
Why does a person hold out instead of drop out of life, love, marriage, parenting, and service? We persevere not because things go so well or because we are so strong. We hold out because of the truth and depth of our relationships, especially our relationship with Christ. If we have come "to grasp fully, with all the holy ones, the breadth and length and height and depth of Christ's love" (Eph 3:18), we will persevere in living for Him. Our relationship with Him will weather all storms, even the storms of persecution (see Mt 7:25).
At Christmas, we celebrate the birth of Jesus. Because He was born, people could touch, see, hear, and feel Him. We can relate to Him — person to Person. Because He was born, we can continue to touch, see, hear, and feel Him in His body, the Church, and especially in the Eucharist, His body and blood. We can relate to Jesus personally and deeply and so hold out till the end of life on earth and the beginning of life forever in heaven.