Sin Consciousness

Some pastors preach that you should not even think about your past sins, is this accurate or even possible?

​Scriptures to note:

Therefore, if any man be in Christ, he is a new creature: old things are passed away; behold, all things become new. 2 Corinthians 5:17

You were taught, with regard to your former way of life, to put off your old self, which is being corrupted by its deceitful desires; to be made new in the attitudes of your mind; and to put on the new self, created to be like God in the true righteousness and holiness.
​Ephesians 4:22-24
 
Here is a trustworthy saying that deserves full acceptance: Christ Jesus came into the world to save sinners—of whom I am the worst. But for that very reason I was shown mercy so that in me, the worst of sinners, Christ Jesus might display his immense patience as an example for those who would believe in him and receive eternal life. 1 Timothy 1:15-16

I was formerly a blasphemer, a prosecutor, and a violent man; yet because I had acted in ignorance and unbelief, I was shown mercy. 1 Timothy 1:13
 
Therefore, I tell you, her many sins have been forgiven—as her great love has shown. But whoever has been forgiven little loves little. Luke 7:47
 
Therefore, there is not condemnation for those who are in Christ Jesus. Romans 8:1

Forget the former things; do not dwell on the past. Isaiah 43:18