Telling myself to stop worrying has never worked, not once. Is there something in Scripture that is actually a method rather than just an instruction?

“And thou shalt remember all the way which the LORD thy God led thee these forty years in the wilderness, to humble thee, and to prove thee, to know what was in thine heart, whether thou wouldest keep his commandments, or no.”

Moses is addressing a generation about to enter the land, and his repeated instruction is to remember: remember the whole way the LORD led you these forty years in the wilderness. Israel's chief spiritual discipline was memory, and it was practised with festivals, stones, and stories precisely because people forget. Remembering is presented as a deliberate act, something you do on purpose, not a feeling that arrives on its own.

“And let the peace of God rule in your hearts, to the which also ye are called in one body; and be ye thankful. Let the word of Christ dwell in you richly in all wisdom; teaching and admonishing one another in psalms and hymns and spiritual songs, singing with grace in your hearts to the Lord.”

Paul gives the Colossians something closer to a mechanism than a mood. Let the peace of God rule in your hearts, and let the word of Christ dwell in you richly, in teaching, in singing, in thankfulness. Every element there is an action with a verb attached. He is describing what you fill a mind with over time, which is a very different project from trying to empty one on demand.