is,

You...
Your actions, your mind,
your body, your soul.
Doing right, abiding in the Spirit, and not giving in to sin, helps you to, "...possess your vessel in sanctification and honour...'.

For this is the will of God, even your sanctification, that ye should abstain from fornication: That every one of you should know how to possess his vessel in sanctification and honour; Not in the lust of concupiscence, even as the Gentiles which know not God...
1 Thessalonians 4:3-5