Jesus has taken care of it all at the Cross.
If you truly believe it applies to you so that you are forgiven, it will change your life. You will be a different person on the inside. The love of God will be shed abroad in your heart through the Holy Ghost (Romans 5:5, Luke 7:36-50, 1 John 4:19), in deed and in truth (1 John 3:18), which will be the fulfilling of the law's righteousness (Romans 13:8-10, Romans 8:4).
Some people have to repent first before they can accept forgiveness (in that in their conscience, it doesn't register that they are forgiven unless they make some kind of commitment to not sin anymore). Others, when they realize they are forgiven through a simple faith in Jesus Christ, simply fall in love with Christ and turning away from sin is the faithful result of that (Luke 7:36-50, 1 John 4:19).