He who loves his life will lose it, and he who hates his life in this world will keep it for eternal life. (John 12:25)
If we love the unregenerate life and despise the new life that is to be found in Christ, we will lose eternal life with Him. Christ is not telling us to hate life, but to hate life without Him. Life is good and we are to love it.
Christ even gives us directions with regard to it: "He who would love life and see good days, Let him refrain his tongue from evil, and his lips from speaking deceit."(1) How are we to hate our lives? The answer is found metaphorically in the previous verse, "Unless a grain of wheat falls into the ground and dies, it remains alone; but if it dies, it produces much grain."(2) We are to die to our old sinful nature. Few verses explain it better than Galatians 2:20, "I have been crucified with Christ; it is no longer I who live, but Christ lives in me; and the life which I now live in the flesh I live by faith in the Son of God, who loved me and gave Himself for me."(3)
Let us not sacrifice the eternal for the temporal - it's simply a bad deal.
(1) Peter 3:10, (2) John 12:24, (3) Galatians 2:20