Php 4:4-7
"Rejoice in the Lord always; again I will say, rejoice. Let your reasonableness be known to everyone. The Lord is at hand; do not be anxious about anything, but in everything by prayer and supplication with thanksgiving let your requests be made known to God. And the peace of God, which surpasses all understanding, will guard your hearts and your minds in Christ Jesus."
The antidote to anxiety: prayer with thanksgiving. The result: the peace of God (eirene tou theou) that surpasses all understanding (hyperechousa panta noun). Peace is not the absence of problems — it is the divine guarding of the heart amid problems.
Php 4:11-13
"Not that I am speaking of being in need, for I have learned in whatever situation I am to be content. I know how to be brought low, and I know how to abound. In any and every circumstance, I have learned the secret of facing plenty and hunger, abundance and need. I can do all things through him who strengthens me."
Contentment (autarkeia) is learned, not innate. Paul 'learned' (emathon) — a school of suffering. 'I can do all things in Christ' is not a promise of material success — it is a declaration of spiritual sufficiency in any circumstance.