It sounds like a cliche: “the power of positivity”. But it is a Biblical principle, and the world often tries to turn Biblical principles into something to scoff at. Consider these verses:
Psalm 118:24 This is the day that the Lord has made; let us rejoice and be glad in it.
Joshua 1:9 Have I not commanded you? Be strong and courageous. Do not be frightened, and do not be dismayed, for the Lord your God is with you wherever you go.”
Philippians 4:8 Finally, brothers, whatever is true, whatever is honorable, whatever is just, whatever is pure, whatever is lovely, whatever is commendable, if there is any excellence, if there is anything worthy of praise, think about these things.
2 Timothy 1:7 For God gave us a spirit not of fear but of power and love and self-control.
Colossians 3:16 Let the word of Christ dwell in you richly, teaching and admonishing one another in all wisdom, singing psalms and hymns and spiritual songs, with thankfulness in your hearts to God.