Romans 12:1
I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service.

The qualifications and specifications for the Jewish sacrifices were laid out very clearly and specifically in the law.  There were certain requirements for the different types of offerings, which animals could be used, how they were killed and what was to be done with the different parts.  But there were also some things that were common among all the offerings that made them acceptable.  And so if we desire to present our bodies as living sacrifices, we must be sure that our sacrifice matches up with God’s specifications.

The main aspect of all the animals offered in sacrifice was that they had no blemish.  They were not to be marred in any way.  Of course, none of us are perfect, and none of us can live a perfect life free from sin.  But it is important to strive for a life without blemish.  We can decide not to commit certain sins.  We can seek God’s forgiveness and cleansing as soon as we realize we’ve done something wrong.  We can trust in the sinlessness of Christ, and God will impart that to us when we believe on Him.  We can separate ourselves from worldly influences and ask God to sanctify us.

Secondly, the people brought their offerings willingly.  No one can force us to seek a godly, righteous way of life.  It must be something we desire in our hearts to do.  We must make the decision every day, maybe even every moment, to offer our lives to God for His service and His glory.  It’s not something we are compelled to do by a set of rules or someone else telling us that we should.  But it should be a genuine, heartfelt desire to give ourselves to God out of love and thankfulness.

Another important aspect of the offerings was that they were done unto the Lord.  People can give their lives to many different causes.  Some people dedicate their lives to their careers, maybe military service, even church ministry.  Our lives should be given as unto the Lord.  Yes, we have jobs to provide for our family’s needs.  We can dedicate our lives to Christian service.  We can spend our lives in a multitude of ways.  But when we are living our lives as sacrifices, our overarching aim should be doing it all for God.

Finally, in all the sacrifices that were done, a life was given.  Blood was shed.  Breathing ceased.  If we want to be a living sacrifice, we have to die to self, die to sin, die to fleshly desires.  Every area of our life must be surrendered to God, given to Him for His uses, His purposes, His plans to be fulfilled.  Every drop of blood should be spent in His service.  Every breath should proclaim Him as the center of our lives.  Our lives are a reasonable thing to offer after all God has done for us.