This is probably the hardest thing we can do. Forgiving ourselves for our pass wrong doings, or are regrets for not doing the right thing at the right time. We are human and like others we fail short.
We destroy ourselves and take the focus off the prize of Christ Jesus when we focus on these things and do not forgive ourselves. God wants us to be his disciples and not dwell on the things that keep us from doing our job.
You know when you start to beat yourself up for past sins or past mistakes, the devil is seeking to distract you from your goal. Just shake the devil off and know there is power in God.
His power overcame sin forever with Jesus dying on the cross. He rose again and God gives us that power to live within us called the Holy Spirit.
Rely on the Holy Spirit to guide you. Get over self and forgive your past, it has made you who you are and God loves you.