If you are a Christian you must live and be different from the world. To be a Christian is to live like Jesus.
1. Paul calls the Philippians children of God (different because of what God has done in our lives). If we have a relationship with God we will be a people of joy, holiness, and we find our identity through Jesus.
2. We are called to be "light" in the darkness of the world. We are to be righteous, truthful, and to do good deeds. Don't hide your difference.
3. Christians are to hold fast to the Word of Life - view the world and its problems through spiritual assessment. The only way to save humanity is through the gospel and the life that Jesus brings (live and bring the gospel to others).
4. We are to live with high moral standards (be blameless and pure). Once we become followers of Christ, we must strive to live this way outwardly and inwardly.
5. Do all things without complaining or arguing. When you complain about your life it reflects the idea of rebellion against God (that you could do a better job than him in leading your life). Look at the source of the complaining/arguing (compare the fruit of the spirit vs the fruit of the flesh) as it can undermine relationships and joy.