If a person wants to give a korban, he can give according to his financial circumstances. If he is financially comfortable, he can give any of the animals. However, if he wants to give a korban and giving an animal sacrifice is too much of a financial burden, he is permitted to give a mincha-offering consisting of flour. In Hashem’s eyes, the donation of the poor man is considered just as precious as the rich man’s ox. From this we can see how Hashem appreciates all that we give of our selves to Him, as long as the intention is from our heart, that is all that matters. Hashem derives satisfaction from the offerings we give Him, not based on the quantity, but based on the quality and the motives one has behind it. This should give us all the inspiration to give whatever we can to Hashem, big or small, the intention in our heart is what qualifies the deed as big or small, not the quantity.