Psalm 51:10 (KJV) "Create in me a clean heart, O God; and renew a right spirit within me."
This Psalm contains a very sincere prayer. David confesses his sin, begs God's forgiveness, and asks God to clean him up. He even asks God not to expel him from God's presence or take the Holy Spirit away from him. When you have the chance, I encourage you to read the whole prayer.
Sometimes we should just get sick of ourselves. David confessed that his sin was ever before him. Our sin often stares us right in the face, and we fail to acknowledge that it's there. Ignoring the iniquity doesn't make it go away; ignoring it causes it to grow. An untreated infection can kill. An unconfessed, unforgiven, and unpurged sin can kill our spirit.
We are so unworthy of God's mercy, yet He gives us opportunity after opportunity to make things right with Him. Whatever "secret sin" you have been holding on to, tell God about it and ask for His forgiveness. He alone can purge you and make you clean. Give the Holy Spirit a clean house in which to dwell. It's time to clean house!