Everything is in their loving Father's hands.
Philippians 4:6-8 (NIV) Do not be anxious about anything, but in everything, by prayer and petition, with thanksgiving, present your requests to God. And the peace of God, which transcends all understanding, will guard your hearts and your minds in Christ Jesus. Finally, brothers, whatever is true, whatever is noble, whatever is right, whatever is pure, whatever is lovely, whatever is admirable–if anything is excellent or praiseworthy–think about such things.
Here is the attitude of the Christian that has a living relationship with the Lord of the universe. They know God is sovereign over all things and loves them dearly. They know they are in the palm of His hand and that nothing can get to them without the Father's permission. If things are difficult or painful, they know that there is good coming from the experience and that the Father will see them through. What peace the child of God should have as they walk through this life!
When troubles come their way, they submit them to God and seek His desired response for them. Once they have discerned the godly response, they act. Then they leave the rest in His omnipotent hands. This understanding and resolve allow God to give us His very own peace. It is peace for our heart, which means our desires are left with Him. It is peace for our minds. We don't have to revisit the problem, again and again, fretting with worry about what we should have done or can do in the future. Your heart and mind are kept in Christ Jesus. He abides in your heart and mind, you yield to His desires and thoughts about your situation. Then your attitude will be entirely different from the flesh. This is when people truly see Christ in you.
Paul adds that we need to keep our minds on what is good. We must take control of our thoughts, dwelling on the things that are uplifting. The enemy of our soul wants us to dwell on the opposite of these. That would be to declare that he has more power than God. Dwelling on the good says that God will prevail. That is the attitude most in tune with Christ, most in line with reality. This will affect your attitude about life, your countenance, and your health, not to mention your daily witness.
Consider: Children of God wear a smile, not because life is easy, but because they know everything is in their loving Father's hands.