“5 But also for this very reason, giving all diligence, add to your faith virtue, to virtue knowledge, 6 to knowledge self-control, to self-control perseverance, to perseverance godliness, 7 to godliness brotherly kindness, and to brotherly kindness love. 8 For if these things are yours and abound, you will be neither barren nor unfruitful in the knowledge of our Lord Jesus Christ.” 

Peter tells us to be diligent in adding these things to our faith: 
1) Virtue  
2) Knowledge   
3) Self-control   
4) Perseverance  
5) Godliness    
6) Brotherly kindness  
7) Love    

If these things are meant to be stacked, as it literally says, then I would start with faith. Basic belief and trust in Jesus. Then I would add virtue to that faith so that I would act with moral excellence while I’m exercising my faith and trust in Jesus. As I’m trying to act with moral excellence, I would add knowledge so that actions I call virtuous are informed by the truth of the scriptures. Then as I am acting in the particular virtue that the scripture guides me in, I add self-control so that even when my flesh wants to take a little time off from virtue, I control myself to be virtuous. Then to that self-control, I add perseverance, so that I remain steadfast in the self-control necessary to walk in informed virtue. Then on top of that I add godliness, which is reverence and respect for God. Then to that I add brotherly kindness, maybe because I might have a tendency to want to, at this point, either set myself apart in an attempt to keep from temptations, or because I’m starting to feel a little holier than my brother. And then top all that off with agape love. 

And IF… I can do this, then I will neither be barren nor unfruitful in the knowledge of the Lord. 

Being barren or unfruitful would be to be devoid of the things my faith should produce. If I claim to know the Lord then it should produce something of His character in me, but apparently, I can be in such a state that my faith doesn’t produce anything. So I need to be diligent in working towards these things so that my life will produce the things it should. Working towards these things will allow the Lord to produce those things in me. 

I believe I have been in such a place that my faith isn’t producing much of God’s character in me. The passage from 2 Peter 1, particularly because self-control was something that came up apart from the scriptures recently, has gotten by attention. I need to add virtue, knowledge, self-control, perseverance, godliness, brotherly kindness, and love, and I need to be diligent about applying those things.