Philippians 4:6 is as much a command from God as any other one that we know about!
Do not fret or have any anxiety about anything, but in every circumstance and in everything, by prayer and petition (definite requests), with thanksgiving, continue to make your wants known to God.
Being anxious, fearful, worried, agitated or stressed out about any situation in our lives is NOT God's plan for us! In fact, it IS sin (a selfish decision to act in a way that is contrary to God's Word). Remember, everything that the God of the Bible instructs or commands us to do is out of His incomparable and irresistible love for us, so that we can stay in position to receive all of His wonderful blessings! Verse 7 tells us the result of obeying verse 6!
And God’s peace [shall be yours, that tranquil state of a soul assured of its salvation through Christ, and so fearing nothing from God and being content with its earthly lot of whatever sort that is, that peace] which transcends all understanding shall garrison and mount guard over your hearts and minds in Christ Jesus.
In order to walk in this great peace we will have to make a decision concerning every thought that come TO us! We must receive the thoughts that come from God and reject the thoughts that do not. If it is contrary to the Word of God, then reject that thought and replace it with one that does! I like this quote by Kenneth E. Hagin:
Thoughts may come and persist in staying, but thoughts that are not put into word or action die unborn.
AMEN! Refuse to speak a negative thought and never act on one! Actively replace those thoughts with what the Word of God has to say! Philippians 4:8 covers this very well!
For the rest, brethren, whatever is true, whatever is worthy of reverence and is honorable and seemly, whatever is just, whatever is pure, whatever is lovely and lovable, whatever is kind and winsome and gracious, if there is any virtue and excellence, if there is anything worthy of praise, think on and weigh and take account of these things [fix your minds on them].
When we do this, THEN we will operate in that wonderful peace of God that will attract the attention of all those without it! Here is Hillsong United with "Prince of Peace":
Shalom in Him!