I know it doesn't make sense. Give up something to get something else better. It is against our nature. But it is wholly in tune with God's nature and God's plan.
The Scriptures are full of examples. Giving a tithe as a sacrifice showing our love and devotion to God and letting God bless us (Malachi 3:10). Giving up your life for Jesus so you won't lose it by trying to keep it (Matthew 16). It is the paradox of how God works in us. But God didn't just SAY this stuff ... God did it! Philippians 2:5-8 is a description of just what Jesus did to both model this Godly behavior and apply what He had given us in His word repeatedly. He gave so we could get something only He could give us.
As I reflected on what, exactly, Jesus gave up (Paul expresses it well here) there was one theme that kept popping into my head. It is Jesus giving something (and modeling something) that seems the most difficult thing for many who desire to call his name. Jesus gave up self.
The first part of this chapter is about the attitude of church people and how we should give comfort, fellowship, compassion, cooperative work (in unity), love, humility and an attitude that looks out for the interests of others. It is a Jesus-focused model for ministry. But now Paul gives us a way to make all of this happen in a perfect way. Paul says, "Have the attitude of Jesus."
Don't think this is both attractive and contagious to those who really want God? I heard a story of a man named John who selflessly served in a faith-based halfway house for people transitioning from jail back into society. John gave time, energy, advice and love to those men who were, to most of society, unlovable. A pastor went to check out the ministry. As he interviewed one of the men about his aspirations after his stay the young man said, "I want to be like John!" The pastor said, "Don't you mean you want to be like Jesus?" The young man said, "If he's anything like John, yes!"
When we give up self for Jesus (after all, He gave up everything for you and me) we don't need to worry about being Christlike ... it just happens! Nuff said!