Like many lists Paul creates in his letters, his list of the fruit of the Spirit in Galatians 5:22-23 should not be taken as exhaustive. Rather, they are nine godly characteristics of those who are filled with the Holy Spirit. They could also be taken as characteristics of Christ.

It is helpful to note that “fruit” is singular while the list that follows is not. We could substitute the word “evidence” for the word “fruit” in verse 22—“the evidence of the presence of the Spirit is.” And peace is a significant part of the evidence of the Spirit’s presence and empowering. That is, if we are anxious and worried, we are displaying evidence that we are not trusting the Holy Spirit’s leading in our life in that situation. How do we maintain peace in trying circumstances? By following Paul’s teaching in Philippians 4:6-7. Instead of being anxious, commit every concern to God through prayer, with thanksgiving, and receive God’s peace in your heart and mind.

If you are anxious, commit your concerns to God in prayer and trust that His peace will replace your worries. 

The Christian should resemble a fruit tree, not a Christmas tree!
John R. W. Stott