The life we lose is the life we live right now that follows the desires of the flesh. We gain eternal life by putting our faith in Christ and receiving the Holy Spirit who give us new desires to please God.
Amy you are absolutely correct. The life that we MUST lose is this life (our desires/agenda, etc). And the reward for doing so is eternal life.
However if you are going to leave eternal life in the realm of salvation by grace through faith you have just placed a contradiction on Scripture, because dying to self is works. This is talking about works not a one-time faith in the Substitute.
The natural or fleshly man (unsaved) does not care what God desires.
This is not talking about unsaved as in destined for the lake of fire forever and ever and ever.
This is talkinga about the people that aren't dying to self. These are forever and ever and ever saved individuals that are walking by the flesh and not by the Spirit. If you are walking by the flesh you do not care what God desires.
But, the born again man has the conviction of the Holy Spirit (because He lives in him) and receives (understands) the spiritual things of God.
Just because a child of God is convicted of the Holy Spirit does not mean they are going to heed that conviction. And the more we rebel the quiter that conviction becomes until God will give you over to the lusts of your mind and death may not be far behind that.
But you are taking a works text and trying to make it fit into a non-works context.