Romans 12:1 & I Corinthians 15:58
When sacrificing an animal according to God's Law, a priest killed the animal, cut it in pieces, & placed it on the altar. Sacrifice was important, but even in the OT God make it clear that obedience from the heart was much more important. God wants us to offer ourselves, not animals, as living sacrifices - daily laying aside our own desires to follow him, putting all our energy & resources at his disposal & trusting him to guide us.
Paul said that because of the resurrection, nothing we do is wasted. But if we maintain a heavenly perspective, we understand that we don't see the good that results from our efforts. Do the good that you have opportunity to do, knowing your work will have eternal results.
Reference summary used from the KJV Life Application Bible, Tyndale House Publishers, Inc., Wheaton, Illinois