What the Holy Bible says about Thankfulness:

16 Rejoice always, 17 pray continually, 18 give thanks in all circumstances; for this is God’s will for you in Christ Jesus. (1 Thessalonians 5: 16-18)

Give praise to the Lord, proclaim his name; make known among the nations what he has done. (1 Chronicles 16: 8)

34 Give thanks to the Lord, for he is good; his love endures forever. (1 Chronicles 16: 34)

Shout for joy to the Lord, all the earth. Worship the Lord with gladness; come before him with joyful songs. Know that the Lord is God. It is he who made us, and we are his; we are his people, the sheep of his pasture. Enter his gates with thanksgiving and his courts with praise; give thanks to him and praise his name. For the Lord is good and his love endures forever; his faithfulness continues through all generations. (Psalm 100: 1-5)

Do not be anxious about anything, but in every situation, by prayer and petition, with thanksgiving, present your requests to God. And the peace of God, which transcends all understanding, will guard your hearts and your minds in Christ Jesus. (Philippians 4: 6-7)