Why should we thank God?

On a mailing list, a person had asked a question “Why should we thank God? We do not keep thanking our parents everyday. And having created us, isn’t it His duty to provide for us? Also, even if we are grateful, doesn’t He know about it without us telling Him? Do we need to thank Him?”
Here is the reply:
God surely has no “utility” of our thanks to Him. Also, God does not depend on our act of thanking Him to know that we are actually thankful to Him. It is for our sake. If we do not get into the habit of thanking Him physically, verbally and mentally, we may slip into a state of ungratefulness. To keep our mind in a healthy state of remembering Him, we need to thank God.
By bringing God into every situation, we will be able to face success with humility and failure with dignity. We will not be carried away by the ups and downs of life. This will take us closer to God. Thus God becomes the way and the goal.