When you accept Jesus into your life everything changes. Why? Because Jesus, via the Holy Spirit, now resides in your heart. Your old "heart" is gone and you are born again.
Not only is there a new found peace and salvation through accepting Christ, but you actually now "want" to do what is always right versus thinking you "have" to.
God's own Spirit will now help lead your life, counsel you as you make decisions, and even discipline you when you make a poor choice (often known as "grieving the Spirit").
Check it out:
“But now, by dying to what once bound us, we have been released from the Law so that we serve in the new way of the Spirit, and not in the old way of the written code.” (Romans 7:6)
“But when he, the Spirit of truth, comes, he will guide you into all the truth.” (See John 16:13)
“But the Advocate, the Holy Spirit, whom the Father will send in my name, will teach you all things and will remind you of everything I have said to you.” (John 14:26)
“It is for freedom that Christ has set us free. Stand firm, then, and do not let yourselves be burdened again by a yoke of slavery.” (Galatians 5:1)
From the moment the Holy Spirit enters your heart, He begins to change you from the inside out. This is a process called "sanctification" and will last your entire life here in earth. He'll not only remind you right from wrong, but will also help you overcome obstacles that are standing between you and a "closer" relationship with God.
When you can't seem to "kick" a particular habit or practice that you feel (or know) is sinful, "pray" to God and ask that the Spirit work on it for you.
Believe it or not, God does "not" want you to conquer this vice on your own. He actually "wants" you to acknowledge you can't do it on your own, and that you need His help. And if He wants to help, why wouldn't you take it?
You make, not only the decision of a lifetime, but of ALL ETERNITY when you surrender your life to Jesus! Rejoice in it, enjoy the process of becoming "more" like Christ each and every day, and rest in the peace that can only come from a life of living for your Heavenly Father.