The last enemy to be destroyed is death. Death is definitively defeated by the bodily resurrection of Christ and absolutely destroyed (presence of death is forever removed) on the Last Day by the resurrection of all flesh; and blessed is he who has a part in His (first) resurrection by faith.
Meanwhile, between the two resurrections, we live in a daily struggle in the presence of life and death. Any sickness of body or soul is a reminder of and an anticipation of death. We may sometimes be completely healthy in body and soul, but there will also be times when we will be completely overwhelmed by pain and suffering in body and soul. The Psalmist describes such a time when his bones are vexed and his soul is sore vexed.
In this extremity the believer calls upon the mercies of God (the blood of Jesus) to deliver him from his vexing enemy, death; the Lord has received his prayer and the Overcomer who lives within has turned back and sore vexed all his enemies.