These last words are Paul's final instructions.
rejoice!: See also Philippians 3:1; 4:4.
Aim for perfect harmony: See study note on 2 Corinthians 13:9. Paul encourages them to aim for restoration.
encourage one another: The need for encouragement is very important in 2 Corinthians, starting with 1:3–7.
be of one mind: Paul encourages them to live in harmony (as in Philippians 2:1–4).