Today is the memorial of St. Martha. In the Gospel reading of John, Jesus told Martha, "I am the resurrection and the life: whoever believes in me, though he should die, will come to life; and whoever is alive and believes in me will never die."
It's clear that there are two lives: the earthly life and the eternal life. If one can never die after this life, then a second death is implied ~ that is the loss of eternal life. Let's make sure that after we die, we'll have eternal life with the Lord and not eternal separation from him. The first life and death are relatively unimportant, while the second life and death are of infinite importance.
The best way to take care of this matter is to love the Lord with all your heart, strength, and soul in this life.