Cultivating a spirit of thanksgiving toward the Ultimate Giver as a first priority in life is a good thing.
By doing so we may come to a far deeper enjoyment of His gifts than we had when we tried to be thankful based only on how much we enjoyed whatever the thing was that He gave us.
In this paradigm, thankfulness precedes and follows the blessing, but the initial gratitude makes the blessing so much fuller.
After all, ultimately, it is receiving the Son of the Giver of all good things as our Lord and Savior that we have to be thankful for the most. Christ, Himself, is the greatest gift any of us will ever know, and receiving Him both precedes and far exceeds any single gift that His Father, in His great love, may grant us afterward.
Oh give thanks to the Lord, for he is good; for his steadfast love endures forever! 1 Chronicles 16:34 (ESV)