I gotta have my orange juice.

While 1 Thessalonians 5 is applicable to all of the Christian life, it has repeated overtones of the weekly public worship service:

• Weekly public worship is one of the several kinds of “day of the Lord” that we can speak of
• As seen in 1 Corinthians, drunkenness and sobriety is particularly applicable to the Lord’s supper
• Our response to church leaders is especially important in the liturgical setting
• Admonishment, encouragement, rejoicing, prayer, thanksgiving, prophecy, and testing-discernment all take place in public worship
• The command to “always rejoice” has particular application to public worship; in Jesus’s presence we have a sort of weekly heavenly furlough from our battle in the world, and are “not [to] be grieved, for the joy of Yahweh is your strength” (Neh. 8:10)
• The focus of the Spirit’s work, and the occasions where we have the most danger of quenching the Spirit, are in the “one another” settings of the whole body of Christ such as public worship

Verse 18 carries similar overtones: in all, give thanks. Translating this as “in all circumstances” or “in all things” is certainly correct; we would not limit its application to public worship. However, it has an intensive application to public worship, where we corporately give thanks to God. And, as the church has recognized throughout history, our giving thanks for the bread and for the wine means that thanksgiving is an appropriate synecdoche for the Lord’s supper.

Thus, weekly communion: in all worship, eucharist!