Because of the Gospel, His Peace Guards our Hearts

6Be careful for nothing; but in every thing by prayer and supplication with thanksgiving let your requests be made known unto God. 7And the peace of God, which passeth all understanding, shall keep your hearts and minds through Christ Jesus." (Philippians 4: 6-7)

Paul gives us the sure-fire way to be freed from cares in our lives.

He did not say: "Tell everyone you meet about your fears."

He did not say: "Take three pills, then call me in the morning".

He said: "Let your requests be made known unto God".

Yet for many of us, we cannot even come to Him, or we fear coming to Him for whatever reason.

Throughout the first three chapters of Paul's Epistle to the Philippians, he talks about the Gospel:

"3I thank my God upon every remembrance of you, 4Always in every prayer of mine for you all making request with joy, 5For your fellowship in the gospel from the first day until now;" (Philippians 1: 3-5)

and

"But I would ye should understand, brethren, that the things which happened unto me have fallen out rather unto the furtherance of the gospel;" (Philippians 1: 12)

and even

"Only let your conversation be as it becometh the gospel of Christ: that whether I come and see you, or else be absent, I may hear of your affairs, that ye stand fast in one spirit, with one mind striving together for the faith of the gospel;" (Philippians 1: 27)

and also

"But ye know the proof of him, that, as a son with the father, he hath served with me in the gospel." (Philippians 2: 22)

The joy, the peace, the righteousness we have in Christ, is all about the Gospel:

"Be it known unto you therefore, men and brethren, that through this man is preached unto you the forgiveness of sins: 39And by him all that believe are justified from all things, from which ye could not be justified by the law of Moses." (Acts 13: 38-39)

The Gospel is all about peace:

"And how shall they preach, except they be sent? as it is written, How beautiful are the feet of them that preach the gospel of peace, and bring glad tidings of good things!" (Romans 10: 15)

and

"For he is our peace, who hath made both one, and hath broken down the middle wall of partition between us;" (Ephesians 2: 14)

and

"14Stand therefore, having your loins girt about with truth, and having on the breastplate of righteousness; 15And your feet shod with the preparation of the gospel of peace" (Ephesians 6: 14-15)

So, when we get to the point where Paul urges all of us to let all our needs be known to God, we can rest assured that He will guard our hearts and  minds, because we have peace with Him. We can come to Him boldly for every need in our lives, too, because of His grace:

"Let us therefore come boldly unto the throne of grace, that we may obtain mercy, and find grace to help in time of need." (Hebrews 4: 16)