Remember, commands are always promises in disguise.
4 Rejoice in the Lord always; again I will say, rejoice. 5 Let your reasonableness be known to everyone. The Lord is at hand; 6 do not be anxious about anything, but in everything by prayer and supplication with thanksgiving let your requests be made known to God. 7 And the peace of God, which surpasses all understanding, will guard your hearts and your minds in Christ Jesus. (Pilippians 4:4-7, ESV)
In other words, God will not command you to do something that is impossible to do, but will provide all you need to live in obedience to what he commands.
Therefore, we have the resources to live free from anxiety.