Every Korban has a special aspect to it called Reiach Nichoach. This can be explained to mean that we are sanctified to God by listening to His commandments. But in truth, we are not giving Hashem anything at all; we are just burning an animal, something Hashem could have trillions of in a moment if He so desired. What is the significance of our one animal to Hashem?
Rabbi Eli Teitelbaum offers the following explanation: What counts is not the animal, but the “sacrifice” – the effort that the person puts into it. That is why when a poor man would bring the Korban Minchah, the cheapest Korban, the Pasuk describes it with the word Nefesh, soul. This poor man could have done many things with the flour involved with the Korban, such as making bread. But instead, his thoughts were about Hashem first. Because of the strain this man caused himself to give his flour to Hashem, it is as though he gave his life.
A Korban can also be ruined easily through a bad thought, such as, “I am wasting my money on this Korban; I could sell this animal or eat it.” This undermines the whole point of Reiach Nichoach, sanctifying oneself to God by listening to His commandments. One should be pleased and happy for this chance to serve Hashem, not upset over losing an animal.
We may not have Korbanot today, but we still have our Tefillah. As we all know, Tefillah parallels and almost replaces the Korbanot. Just as we needed our Nefesh for the Kobanot, we need it for our Tefillah. We must pray with all our hearts, and understand and feel what we are saying.