Brothers, join in imitating me, and keep your eyes on those who walk according to the example you have in us. (ESV)
Are you the kind of person that others should imitate? As you consider your lifestyle would others look at you and say, "Now, that's what a Christian should look like."? Maybe you think that because you are not perfect it does not matter whether or not you are a good example for others to follow. While it is true that you are not perfect, there is a need for you to be an example for others as you follow those who are an even better example than yourself.
Paul instructs the believers at Philippi to imitate him. We often think of the Apostle Paul as a great teacher. We have his many epistles in the New Testament and gain much of our doctrinal instruction from Paul's writing that was inspired by the Holy Spirit himself. However, the most effective teaching is modeled, not written. Paul had modeled for the believers in Philippi how they should act.
In the previous verses in this chapter Paul has laid out the need to continue the race that we have begun with Christ. We are to leave the past behind and press on toward the goal of perfect righteousness in Jesus. Paul is saying that he is an example of one who is pursuing this walk of righteousness, and there are others. Recognize their maturity and follow them!
This kind of Christian imitation is severely lacking in the church today. There aren't enough good models of Christ-like behavior. In Paul's letter to Titus, in Chapter 2, he spells out how the older men are to be examples to the younger men. The older women are to be examples to the younger women. If we want to see our culture change we need to be better models and follow better models.
Ask the Lord to show you what kind of model you are for others. If you are not living a life that others should imitate ask the Holy Spirit to help you to change so that you can be.