Bear in mind that the Israelites were in the wilderness, they were depending on God for their daily bread, literally, and they were bound for a new land where they would need flocks and herds, God required them to sacrifice the very animals they would need to establish themselves well in the Promised Land.
Think about the faith required to put to death the very things you would need to build a life in the Promised Land. Recall that God carefully prescribed that only the best be used for sacrifice - no culling the weak and lame from the flock. Based on the numbers provided, they had an abundance of animals with them; but it is human nature to want more and to seek to hold on to all that we have. Especially the best of the best. Even if we have enough for today, we desire to set something aside for the future, not even knowing if we will be around to enjoy it. The notion of giving God our first and best is challenging, even for those of us facing mostly "first world problems." Maybe especially for us.
I love the way our pastor, JD Greear, put it in a recent message from Malachi (or as he says, "the Italian prophet, Ma-lah-chee"), "To what or whom do you give your first and best? The first and best of your time? Of your gifts? Of your finances? Whatever gets your first and best, THAT is the object of your worship."
For me, offering my first and best means spending time in God's Word first thing in the morning. It means giving financially what God has led us to give before we pay the first bill. How do you offer your first and best to God? What does that look like in the context of your life? How can we encourage one another to put God first?