If you go to any bookstore there are volumes of books on how to find serenity and happiness.  Very few people realize that in Paul's letter to the church at Philippi the 4th chapter gives a plan for a serene life.

1) A Heavenly Future - 4:1  The apostle had just finished writing about the glorious state of heaven and the desire we have to see the Lord.  He uses the term "therefore" to write to his "joy and crown" who would also share in this if they remain faithful.  The same thought is expressed in 1 Thess 2:19.  That is serenity.

2) We Are Loved - 4:1 - Love is also a source of serenity.  Paul addressed them initially as my beloved and longed for brethren.  That is a serene feeling.  Paul truly had them in his heart 1:7 Most importantly we are loved by the Lord

3) Stand Firm In The Faith - 4:1 - In many verses in this chapter Paul repeats the idea of being in the Lord.  How could you find serenity outside of the Lord?  Happiness is in Christ. We stand firm by being "in the Lord" (abiding in the Truth) 2 John 4,6,9 But remember, we must STAND. 1 Cor 16;13; Gal 5:1;
1 Thess 3:8

4) Get Along With Others - 4:2 - Maintain the right relationship!  Divisiveness is a terrible thing often condemned in the Word.  How could you have serenity with clashes in the Lord's Body? 1:27; 2:2

5) Stay Busy! - 4:3 - Notice how Paul called Euodia, Synteche, etc his "fellow workers". Eph 4: 15-16
This cures cynicism, pessimism, boredom and other like problems that keep someone from serenity.

6) Your Name Is Enrolled In The BEST Book - 4:3 - What greater joy is there knowing your name is enrolled in heaven!  That brings serenity!

7) Rejoice! - 4:4 - Romans 14:17; Acts 2:46-47  Happiness is OURS! Claim it! Galatians 5: 22-23
How can we do it all the time?  Romans 8:28  Rejoice always! That is serenity!

8) Develop an attitude that is gentle, sweet, forbearing, reasonable, considerate, courteous, gracious, meek, etc, etc. - 4:5 Some say "that's just not the way I am".  Well, change and become that way!

9) "The Lord Is At Hand" - 4:5 He is ever-near.  He is always close by.  Of course He could come at any time in the sense of the second coming, but here serenity comes from knowing He is close to us at all times!  Psa 34:18;  119: 151;  145: 18-19; Acts17: 27.  That gives us a sense of serenity!

10) "Be Anxious For Nothing" - 4:6-7; Mt 6: 25-34  We really can live a worry-free life!  "If you only knew MY problems!  Don't be so naive!  You would be shocked to know what has happened and is going on in the lives of others!  Be serene!

11) Control what You Think About - 4:8 Control your thoughts, don't let your thoughts control you!

The rest of the chapter deals with personalizing that serenity, who provides it and how truly wonderful it is!  Serenity!