You bring up some very interesting points concerning penance. Most Protestants have a very strong aversion to this practice, but it needn’t be so. The worst part about confession is the anticipation. In the confessional, all is laid bare. There is no denying your sinfulness or skirting the issue. You have to come out and breathe your darkest secrets and blackest sins. The relief afterwards though is incredible. It is actually one of the best feelings I have ever had. The sin is gone, vanished, as if it never happened. The gift of confession is a clear conscience. I think that is why Jesus instituted this practice through the Church. Jesus understood our human nature and wanted us to be able to live in the perfect freedom he intended, without a guilty conscience. You bring up secular counseling in your post. Again, I think this goes to proving the point about confession. In today’s society, people pay thousands of dollars to professionals so that they can tell them their problems. For a Christian, you can go to one of Christ’s priests and lay your guilt, your anxiety, your problems, and your sins on them free of charge. Concerning specific penances, each time I’ve gone to confession, the priest has prescribed prayer as a penance. Once (when I told the priest that I had failed to pray or read the scriptures) I was basically told to take a walk outside and sit under a tree and read the Bible. So, rectifying a sin is also a big part of the penance process.
When you begin to examine penances you can see the superabundant graces that are part of the system of forgiveness. You asked ‘has serving a pennance after confession helped improve the situation in your faith?’ For me, relief comes immediately after confessing sins, before I even undertake penances. The sin is already gone when you undertake penance. So when you do penance after confession you can feel God’s grace being poured out upon an entirely immaculate conscience. It is then that you realize how free God is with His grace for those who seek it. Penance adds grace upon grace.
Something else you may find interesting is the experience I’ve had with penances undertaken apart from confession. There have been times when I didn’t want to confess my sin, so I would undertake a penance without going to the confessional, in order to try and get rid of the sin. Whenever I have done this, it has always made me feel worse. When I did penance in this fashion it served only to convict me of my sin without offering any relief for my conscience. If you have ever read ‘The Scarlet Letter’ there is any interesting example of this phenomenon in the person of Arthur Dimmesdale. Dimmesdale is the minister who commits adultery, only no one knows that he did it except for the person with whom he committed adultery. Throughout the book, his conscience is tortured by his sin, he is totally racked with guilt and becomes severely ill. He undertakes all sorts of severe penances, yet they all make him feel worse. He scourges himself, fasts to the point of near starvation, holds all night vigils, and does a number of other things to try to ease his guilt. None of them work.
I have found this to be true in my own life. Only penance or indulgences undertaken for already forgiven sin are of any value. This is why no one could be saved under the Law. The Law serves only to convict people of sin. The Jews were trapped in a system of ceremonial cleanness and works righteousness that couldn’t bring forgiveness of sins. Jesus shed his blood so that the inscrutable riches of God’s grace and mercy could be opened to us. Confession opens up flood gates of grace and wipes our conscience entirely clean. Imagine, in the moments after confession you are entirely sinless, perfect, free of all guilt, almost like an angel. Confession is difficult for Protestants and Catholics though. We want to stay in the darkness because our deeds are dark. Confession shines God’s light on your darkness, which is painful, but afterwards only light remains. Penance serves to brighten this light further. I hope this answers your question.