They say repentance is having a change of heart and/or mind. If you're just turning to Christ, that is repentance. You've been convicted by the Holy Spirit as a lost sinner and you choose to believe and submit to the Lordship of Jesus. You turn to the Lord. A non believer cannot clean himself up or change himself for Christ. He just turns to the Lord.
As a believer, the Holy Spirit gives us a sense of right and wrong in our spirits. We sense discord within us as we move to the left or to the right. We want to walk in the peace of God. We want to walk by faith. If our conscience is bothering us, it's hard to walk by faith.
Often as we walk, God gives us a sense on the inside when we grieve His Spirit. He may remind us of something we did or didn't do. We know that we missed the mark. That's what sin is. Missing the mark. If their are known boundaries and we cross them, that's "tresspassing". If you know certain things are sinful or abmoninable to God, and you do them anyway, that's being a transgressor. God doesn't like any of this, but knows that we will do it from time to time. He knows when we are tested, if we are walking in the flesh, that we will fail the test.
Sometimes in the preaching of the Word, we become convicted of something we fall short in, or should have been doing. We ask forgiveness and purpose not to do it again.
I ask to be cleansed in His blood and that I may know pure fellowship again. Usually within seconds, their is a difference on the inside as I put faith in His Word and in His blood that He will forgive me. If you don't really feel it, you still have to go by faith. As you walk in faith, you'll begin to bear fruit.
If we persist in deliberate sin, there can be a "searing" process whereby your conscience does not hear the Spirit of God. Sometimes God will let you walk with Him still as you miss the mark in some areas, but you don't really sense the move of His Spirit, you don't know that sensitivity of heart. It's good to ask Him where you've missed it, then confess it as sin, and purpose not to do it again. Receive forgiveness and go forward in faith, believing in His faithfulness.
I believe that as we purpose to walk closely with God, that He increases our sensitivity to what grieves Him. If we obey, we can bear more fruit.
Personally, I believe that God has many things that He would deal with us about, but their is a timing involved that only He knows. He knows how and when you need to change and yield a certain way. He may convict you of something that seemingly was OK just yesterday. The more we cry out for a closer walk, the more of ourselves we often have to deny.
You have to have faith in the sincerity of your repentance too. Even though you may have fallen for the same thing (yet) again, when you repent, you have to believe that even you meant it and walk as you should from that moment on. Sometimes those first few steps of faith following your asking forgiveness take some real deliberation. I usually make a declaration of the Blood of Jesus cleansing me. I might declare myself the righteousness of God in Christ (totally by brace) just to set my oar in the right direction to guide the ship! Thank God for His mercy.