The opposite meaning of thankful is ungrateful. Look at the ways the Jews behaved. They had everything they needed, and they were still ungrateful. Exodus 16:2 “And the whole congregation of the people of Israel grumbled against Moses and Aaron in the wilderness.” God provided them with everything they needed but they were still upset and complained all the time.
Thanksgiving is a time about giving thanks to the Lord for all He has provided you. Thank him for everything you have like your water, house, food, and your Bible. Psalm 107:8-9, “Let them give thanks to the Lord for His unfailing love and His wonderful deeds for mankind, for He satisfies the thirsty and fills the hungry with good things”.
The world has turned Thanksgiving into something else. Some people think Thanksgiving is about eating turkey and having the family over. Those are great things, but the true meaning of Thanksgiving is about thanking the Lord for all that you have. Don’t be ungrateful like the Jews, but be thankful for all the Lord has done for you.