"Rejoice always, pray continually, give thanks in all circumstances; for this is God's will for you in Christ Jesus." (1 Thessalonians 5:16-18)
About times and dates Paul has no need to write: the Thessalonians know that the day of the Lord will come like a thief in the night. When people are saying peace and safety, destruction will come on them suddenly. But they are not in darkness so that this day should surprise them like a thief. They are children of the light and children of the day. So let them be awake and sober: putting on faith and love as a breastplate and the hope of salvation as a helmet. God did not appoint them to suffer wrath but to receive salvation through the Lord Jesus Christ, who died for them so that, whether they are awake or asleep, they may live together with him. Therefore encourage one another and build each other up.
Paul's final instructions are the most compressed and most quotable summary of the Christian life in the entire NT: Rejoice always, pray continually, give thanks in all circumstances; for this is God's will for you in Christ Jesus. Three imperatives, three words each, the totality of the interior life. Not pray sometimes, not rejoice when things are good, not give thanks for the pleasant things. Always, continually, in all circumstances. The Catechism identifies this triple call as the programme of the life of prayer: joy as its atmosphere, continual prayer as its breath, thanksgiving as its constant orientation (CCC 2742). Do not quench the Spirit. Do not treat prophecy with contempt. Test everything, hold on to what is good, reject every kind of evil.
The closing benediction is trinitarian and total: may the God of peace himself sanctify you through and through. May your whole spirit, soul, and body be kept blameless at the coming of our Lord Jesus Christ. The one who calls is faithful, and he will do it.
Brothers and sisters, rejoice always, pray continually, give thanks in all circumstances. This is God's will for you. Not a counsel for the spiritually advanced. Not an aspiration for the future. God's will, for you, now. Begin with the easiest: give thanks. Name three things in the last twenty-four hours for which you are genuinely grateful. That is the beginning. The rejoicing and the praying will follow from there.
God of peace, sanctify us through and through. May our whole spirit, soul, and body be kept blameless at the coming of our Lord Jesus Christ. Let us rejoice always, pray continually, give thanks in all circumstances, for this is your will for us in Christ Jesus. You who call us are faithful, and you will do it. Through Christ our Lord. Amen.