How then can we let go of that sin that we hold and let God fill it with something else? Like I said before it is easier said than done. The devil wants you to keep on thinking that whatever you are doing is okay and there is nothing wrong with it. He wants you to feel so comfortable with whatever it is that you are doing so that you silence the voice of the Holy Spirit.
I believe that the very best thing that we can do is to pray and keep on praying. If you feel the urge or temptation to do that "secret sin" you have to pray immediately for God to remove it from your heart. Then you need to remind the devil that you are dead to that sin and you are now walking in the right way. He will try to remind you how fun it was and how much you enjoyed it, but go to Jesus and ask Him to send the devil away and He will!
Sometimes though we can be stubborn and want our own way, and the devil is successful at leading us back into that sin, when we realize what we have done (which is sometimes in the process of doing whatever it may be) we must go to Jesus and tell Him how sorry we are and to ask for forgiveness and ask Him to help us to overcome in all points of weakness. The Bible tells many different promises of how Jesus will come to help us no matter what.
Jesus said He would send every angel in heaven if it meant that we would be saved and not fall into temptation! Every angel! Sometimes I can't fathom the love of God and understand how He can put up with such a weak and erring child like I am, like we all are. But God does love us more than we can ever know, it will take us all eternity to discover how much He really does love us, and even then we won't know everything.
Yes, we do need to let go and let God run our lives, no matter how hard it may be and no matter what difficulties we may overcome. God will help us in all of our weaknesses and He will keep us from falling like He has promised He would in His Word.
Another thing to keep in mind is, while we may think that we are doing this sin when no one else is looking, all of heaven is watching us, watching to see what choices we make. We can think of Jesus and how He died so that we could be totally free from sin. We can think of how Jesus cries when He sees us doing those things that displease Him. Also that the angels and the other unfallen worlds would be disappointed in us.
If we can keep these things before our minds, we would be less likely to fall/stumble. We can also remember that if we are faithful unto the end, Jesus will give us the crown of life and we can be with Him forever. Jesus himself said, "What is it if a man gains the whole world but loses his soul" (paraphrase).
When we think about it, or at least when I think about it; I realize that it isn't worth it to lose all of eternity for just a moment of pleasure. For me what matters most is that in the end my Savior says, "Well done good and faithful servant!" I want to do everything in my power to have Him say that, even if it means giving up on what I may consider pleasure. After all I'm giving it up for Him!
I want to let go and let God, don't you?