A person was required to offer up a thanksgiving-offering whenever he or she experienced some open example of G‑d’s protection or help.
Always Being Thankful
אִם עַל תּוֹדָה יַקְרִיבֶנּוּ וגו': (ויקרא ז:יב)
If [a person] is bringing [a sacrifice] in order to give thanks . . . Leviticus 7:12

In the Messianic era, communal sacrifices will continue to be offered up, but there will no longer be personal sacrifices. The sole exception will be the thanksgiving-offering. Similarly, we are taught that in the Messianic era, all forms of prayer will cease except for prayers of thanksgiving.

The purpose of personal sacrifices (other than the thanksgiving-offering) is to orient our animal soul toward Divinity. Once the process of atonement will have been completed – and we will no longer have the desire to sin – these types of sacrifices will become obsolete. Only the thanksgiving-offering will remain, for its function is to express our acknowledgement of our dependence upon G‑d, and this will continue to be the case.

Similarly, we will no longer need to pray for our needs: we will not lack anything, illness and poverty will be matters of the past, and harmony and spiritual sensitivity will become the hallmarks of society. Prayer will consist only of giving thanks, as we continuously acknowledge G‑d’s benevolence and wonders.

We can hasten the Messianic era by emphasizing in our present lives what will be true in Messianic times. Thus, by placing the emphasis in our prayers on appreciating G‑d’s goodness, we hasten the time when this will indeed be our prayers’ sole focus.1