Know this, Traveler: people are not seized in the streets, thrown into cages, and at the appointed time, dragged kicking and screaming to our altars. One is chosen, he or she is told by the priests that he or she is chosen, and the Chosen One walks, voluntarily, with pride and dignity, to give his or her service. In some cases - I have known it to happen - a Chosen One says, "No, I do not wish to give my service. I refuse." If this happens, a substitute is found. Great warriors captured in battle have been offered their freedom or even commissions in their captors' armies, and have instead demanded their right to be sacrificed.
You have heard, perhaps, that many of those sacrificed are those captured in battle. This is true.

Tlaloc, Lord of the Storm