A Thanksgiving meditation from Scripture and the Book of Common Prayer:

Rejoice in the Lord always; again I will say, Rejoice. Let your gentleness be known to everyone. The Lord is near. Do not worry about anything, but in everything by prayer and supplication with thanksgiving let your requests be made known to God. And the peace of God, which surpasses all understanding, will guard your hearts and your minds in Christ Jesus. – Philippians 4:4-7 (New Revised Standard Version)

From the book of Common Prayer:

Accept, O Lord, our thanks and praise for all that you have
done for us. We thank you for the splendor of the whole
creation, for the beauty of this world, for the wonder of life,
and for the mystery of love.

We thank you for the blessing of family and friends, and for
the loving care which surrounds us on every side.

We thank you for setting us at tasks which demand our best
efforts, and for leading us to accomplishments which satisfy
and delight us.

We thank you also for those disappointments and failures
that lead us to acknowledge our dependence on you alone.

Above all, we thank you for your Son Jesus Christ; for the
truth of his Word and the example of his life; for his steadfast
obedience, by which he overcame temptation; for his dying,
through which he overcame death; and for his rising to life
again, in which we are raised to the life of your kingdom.

Grant us the gift of your Spirit, that we may know him and
make him known; and through him, at all times and in all
places, may give thanks to you in all things. Amen.