What is self-forgiveness?

Do we have the power to forgive ourselves? 

How then do we move past the shame we have for the things we previously did without self-forgiveness?

Romans 6:20-23

20 For when you were slaves of sin, you were free in regard to righteousness. 21 Therefore what benefit were you then deriving  from the things of which you are now ashamed? For the outcome of those things is death. 22 But now having been freed from sin and enslaved to God, you derive your  benefit, resulting in sanctification, and the outcome, eternal life. 23 For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord.

1 John 1:9

If we confess our sins, He is faithful and righteous to forgive us our sins and to cleanse us from all unrighteousness.

Philippians 3:13

Brethren, I do not regard myself as having laid hold of it yet; but one thing I do: forgetting what lies behind and reaching forward to what lies ahead,