The definition of the word, "SACRIFICE"? Dictionary, SACRIFICE: "is an offering of any animal, human life or any thing or kind to a deity or divine being (GOD) in PROPITIATION, ATONEMENT, SATISFACTION or HOMAGE".
Bible:Romans 12:1,1 Peter 2:5,Joel 2:12)Hebrews 13:15 "Through Him then, let US continually OFFER up a SACRIFICE of praise to God, that is, the fruit of lips that give thanks to His name." Very clear we could continually OFFER OUR PRAISES, fastings(human acts) and bodies to God as SACRIFICES. To connent the dots:Now I rejoice in my SUFFERINGS for your SAKE, and in my flesh I COMPLETE what is LACKING in Christs afflictions for the SAKE of his body, that is, the church (Col 1:24-25). Very Biblical.