I feel bad for all the things that I did before I was born again. The guilt makes me feel bad as a person even though I am free and redeemed. How can I stop thinking about that and think about all God has for me and to see my calling and where to serve God?
The FIRST thing that you need to realize is that the "Voice" (internal or external) that rips, tears and condemns you, and tosses all the garbage up - isn't God's Voice at all. it's the enemy (the messenger of satan) who HATES YOU, and all you stand for.
And when you realize THAT, then realize that you
don't have to listen to it, since it's only PURPOSE is to destroy you, and your relationship with God.
SO - tell the enemy to take his condemnation and judgmentalism and stick it where the sun don't shine. yell at him if you feel like it (probably not in public, lest people begin to wonder), and
remind your ENEMY just WHO YOU ARE in Christ - i.e. PERFECT in God's sight, and cleansed from ALL sin by the Blood of Jesus sacrifice, and in possession of the very righteousness of JESUS (which is the ONLY REAL righteousness you'll ever have).
Of course if there's "Practical restitution" to be made in any situation, then MAKE IT to the degree that you can. IF a situation is Non-Reversable (as some situations are) then face that fact, and move on.
Just imagine what Paul went through after years of destroying Christians - and then winding up as the "Apostle of Christ the Gentiles". HE had his OWN "Messenger of satan" screaming in his ear too. We All do.
It takes a bit of practice, and in one respect, the "Normal Christian Life" DOES require some mental hygene, and the ability to say "NO" when you should.
I remember a pastor years ago in Michigan, who had a "Besetting sin" (I don't know what it was) that he tended to fall into. And after he did it AGAIN. he repented - AGAIN, and cried out to the Lord that he was sorry that he'd "done it again". And the holy Spirit said: "done WHAT again??"
WHen you repent in faith the sin is GONE (farther than the East is from the West). Of Course SATAN remembers it, and LOVES to toss it in your teeth every chance he gets. But God doesn't.
Simple as that.