In my opinion, thanksgiving prayer is very important. We know that God is Almighty. He can make what is impossible for man, to become possible. God is beyond the time and space. Therefore, everything is possible to Him.
We can pray to God and ask for the things for the future, why can’t we thank to God for what He had done on us before? Maybe, what we receive now, is because of the prayer of thanksgiving tomorrow.
Therefore, we should have a grateful heart to God always.