Our original text, if you haven’t lost sight of it, was, or is, “for if ye live after the flesh, ye shall die: but if ye through the Spirit do mortify the deeds of the body, ye shall live” (Romans 8:13). Note the method of mortification here, “through the Spirit”, for you can’t mortify the very least of your sins without the Holy Spirit, not even the slightest motions of sin (Galatians 5:16). By the Spirit we understand to mean the graces of the Spirit, these are they by which mortification is carried out, by his immediate efficacy. So you need to cherish grace in the heart in order to mortify original sin with its habitual lusts. The grace that is opposite to the predominant lust must be encouraged, grown. If it is pride, then set yourself especially to study humility; if it’s worldliness, then heavenly mindedness; if passion then meekness. Look for what sin is most advantaged by your natural bent and set yourself against it, else you will never excel in spiritual growth, stature, you will remain a spiritual dwarf all your days. A little grace will go far, when grace has to row against the wind and the tide, it must needs be strong.