1. Concerning the Christian life (1 Thes. 4:1-12
FSJ

2. Outline Exhortation to grow (4:1-2) Exhortation to holy living (4:3-8)
Exhortation to love (4:9-10)
Exhortation to live a decent life (4:11-12)

3. Introduction Paul’s prayer
Now may God our Father himself and our Lord Jesus direct our way to you. 12 And may the Lord cause you to increase and abound in love for one another and for all, just as we do for you, 13 so that your hearts are strengthened in holiness to be blameless before our God and Father at the coming of our Lord Jesus with all his saints. (1 Thess. 3:11-13 NET).

4. Exhortation to grow (4:1-2)
Finally then, brothers and sisters, we ask you and urge you in the Lord Jesus, that as you received instruction from us about how you must live and please God (as you are in fact living) that you do so more and more. 2 For you know what commands we gave you through the Lord Jesus.

5. There was growth: as you are in fact living
1 Thes. 1:2-3: We thank God always for all of you as we mention you constantly in our prayers, because we recall in the presence of our God and Father your work of faith and labor of love and endurance of hope in our Lord Jesus Christ.
1 Thes. 2:13-14: And so we too constantly thank God that when you received God’s message that you heard from us, you accepted it not as a human message, but as it truly is, God’s message, which is at work among you who believe. For you became imitators, brothers and sisters, of God’s churches in Christ Jesus that are in Judea, because you too suffered the same things from your own countrymen as they in fact did from the Jews, 

6. Why the exhortation? There is a need for a reminder
There is a need to continue to live and please God (cf. 1 Thes. 2:4)
There is always room for growth (Cf. 1 Thes. 3:10; 4:10)

7. Exhortation to live a holy life (4:3-8)
The basis (v. 3a) – the will of God
Application (v. 3b-6)
that you keep away from sexual immorality (1 Thess. 4:3 NET).
that each of you know how to possess his own body (skeuos, vessel) in holiness and honor… (1 Thess. 4:4-5 NET)
In this matter no one should violate the rights of his brother or take advantage of him, solemnly. (1 Thess. 4:6 NET).
The reasons (v. 6b-8)
because the Lord is the avenger in all these cases, as we also told you earlier and warned you (6b)
For God did not call us to impurity but in holiness.(v. 7).
Consequently, the one who rejects this is not rejecting human authority but God, who gives his Holy Spirit to you. (v. 8)

8. Exhortation to love (4:9-10a)
Recognizing the good that was going (9a)
Now on the topic of brotherly love you have no need for anyone to write you (9a),
Taught by God (9b)
for you yourselves are taught by God to love one another (v 9b).
Practicing towards others (v. 10a)
And indeed you are practicing it toward all the brothers and sisters in all of Macedonia (v10a).
Need for growth (10 b)
But we urge you, brothers and sisters, to do so more and more, (10b)

9. Exhortation to live a decent life (4:11-12)
aspire to lead a quiet life, (v. 11a)
“Besides, the worthless man whose life is one long restlessness haunts market-places, theatres, law-courts, council-halls, assemblies, and every group and gathering of men; his tongue he lets loose for unmeasured, endless, indiscriminate talk, bringing chaos and confusion into everything, mixing true with false, fit with unfit, public with private, holy with profane, sensible with absurd, because he has not been trained to that silence (quiet life) which in season is most excellent.” (Philo, De Abrahamo 20).

10. Exhortation to live a decent life (4:11-12)
  attend to your own business (v. 11b)
work with your hands (v. 11c) as we commanded you
In this way you will live a decent life (in a fitting manner) before outsiders and not be in need. (v 12)

11. Conclusion
“The obedient Christian will have a holy life by abstaining from sexual sin; a harmonious life by loving the brethren; and an honest life by working with his hands and not meddling in the affairs of others. When unsaved people see Christ magnified in this kind of a life, they will either oppose it with envy or desire to have it for themselves. Either way, God is glorified.”
Warren W. Wiersbe