Paul reminds the Galatians and us that he is an apostle sent by Jesus Christ and God the Father. Paul did not, in his own flesh, decide to be an apostle to the Gentiles. He was chosen for God for this specific task.
I am talking to you Gentiles. Inasmuch as I am the apostle to the Gentiles, I take pride in my ministry—Romans 11:13 (NIV)
Then Paul goes on to remind them and us that we have grace and peace from God our Father and the Lord Jesus Christ. Encouraging each other is something we should practice everyday until it becomes a habit. In the turbulent society that we live in today, we all need encouragement and a reminder that there is a safe harbor for us to come to when we need rest and peace.
8 In peace I will lie down and sleep, for you alone, Lord, make me dwell in safety.—Psalm 4:7 (NIV)
10 He died for us so that, whether we are awake or asleep, we may live together with him. 11 Therefore encourage one another and build each other up, just as in fact you are doing.—1 Thess. 5:10, 11 (NIV)
Peace and rest are just two of the gifts we receive because we are joint heirs with Jesus. His obedience to death on the cross brought glory to the Father. Our obedience in living for Jesus will bring more glory to the Father forever and ever.