The materials and energy that make up our bodies is already immortal. Upon death it will move on to be apart of something else. From both the spiritual and material sense this is the case in the form of a soul moving on or the atoms that make up your body. Anyone that wants to live in this life forever I strongly suspect they are in fear of what comes after, or the lack of anything coming after in the form of our consciousness moving on. Who knows what is next all I know is that it will probably be similar to what it was like before birth.