In our society, we have institutionalized the practice of gratitude. People say "thank you" without thinking, and without any genuine sense of thanks. It's become a meaningless courtesy, like "Goodbye," which originally meant "God Be with Ye."
“Please, Lord our God, do not make us dependent on the gifts or loans of other people, but only on Your full, open, holy and generous hand…” -- The Koren Sacks Siddur, p.982
It is a mitzvah to bless God before and after meals. The order of Birkat HaMazon takes us on a journey through various modes of thanksgiving as we see above from the third blessing, the blessing for Jerusalem.