Finally, brethren, whatever is true, whatever is honorable, whatever is right, whatever is pure, whatever is lovely, whatever is commendable, if there is any excellence and if there is anything worthy of praise, think about these things. The things you have learned and received and heard and seen in me, practice these things, and the God of peace will be with you. –Phil. 4:8-9
Here, the apostle Paul is closing out his letter to the Philippians. Previously, in chapter 3, he says he doesn't mind repeating himself concerning what is important to him (v.1). So, what is worth repeating? The "surpassing value of knowing Christ" is (v.8). Therefore, everything else Paul says falls under this idea of knowing Christ and letting Christ pattern our lives. That's why he says in verses 14-15 to "have this attitude" of "press[ing] on toward the...upward call of God in Christ Jesus," and in verse 16, "[L]et us keep living by that same standard to which we have attained," and in verse 17, "[J]oin in following my example, and observe those who walk according to the pattern you have in us." So, in the last two chapters of Philippians, Paul is constantly referring to a pattern of living to which we all aspire out of the motivation to know Christ more deeply.
Now, this pattern of living teaches us to master life by the power of Christ rather than let life master us. Life should not dominate us; we should dominate life. Accordingly, Paul instructs his readers to rejoice in the Lord (4:4), not to be anxious (v.6a), to pray (v.6b), to let Christ guard our hearts and minds (v.7), and to discipline our thoughts (v.8). We are to think about true, honorable, right, pure, lovely, commendable, excellent, and praiseworthy things. We should purposely discipline our thoughts and lives in an effort to know Christ more deeply. When we aspire to this pattern for life, we experience peace, and "the God of peace will be with [us]!"