15 Look carefully then how you walk, not as unwise but as wise, 16 making the best use of the time, because the days are evil. 17 Therefore do not be foolish, but understand what the will of the Lord is. 18 And do not get drunk with wine, for that is debauchery, but be filled with the Spirit, 19 addressing one another in psalms and hymns and spiritual songs, singing and making melody to the Lord with your heart, 20 giving thanks always and for everything to God the Father in the name of our Lord Jesus Christ, 21 submitting to one another out of reverence for Christ. (Ephesians 5)
Paul has just made a stark contrast between "living in the light" of Christ and dying in the darkness.  There is a day and night difference. As he continues on here, a distinctive characteristic of living in the light is ongon thanksgiving - alwas and for everything.  Thankful people are careful people - careful not to do things that displease the Father, and careful to consider others in all they do. As followers of Christ, this practical thankfulness should mark everything we do. It is not just something we say or think; it permeates the way we live.