In this portion of scripture, the Apostle Paul was imploring the believers in Rome to commit their lives to the Lord which means dedicating and pledging their lives to him. So when scripture says present your bodies as a living sacrifice, it does not just mean the flesh, but body, spirit and soul (our total being), willing to forsake the worldly pleasures of this age. So Romans 12:1 reminds us as believers to honor the Lord with our total being, our complete existence, we must take care of the temple He has given us, our bodies (which consist of our will, mind and emotions). Since our thoughts come from and are processed through our brains as well as our emotions (feelings), I believe the mind and emotions can be considered a part of the "flesh. We must guard it diligently, it must not be abused.
In our daily Christian walk, what does this verse actually mean to us? Beloved it means that for those of us in Christ Jesus by virtue of being saved by grace, the only acceptable spiritual worship to God is to offer ourselves completely to the Lord God. We must be instruments or vessels of righteousness ready to be used by Him at any time or place. I like how this one author put it in her article from the King's Highway, she states " we must give God permission to walk through us and expose anything in us that is not of faith. God is a gentleman and He will not force us to do this without our permission." So true, I could not have said it any better, the Christian faith is a faith of "free will" you have to be willing to go all the way with the Lord once you say " I accept you as my Lord and Savior" being ready to surrender completely. The Lord has set us apart as His holy people, His prized possession and therefore we must as His people honor Him, worshipping Him in spirit and in truth.
"For you are a holy people belonging to the LORD your God. The LORD has chosen you to be His prized possession out of all the peoples on the face of the earth." Deuteronomy 14:2
"But a time is coming and has now come when the true worshipers will worship the Father in spirit and in truth, for the Father is seeking such as these to worship Him. " John 4:23