HOW DOES A SINNER REPENT ?

In Mishneh Torah Hilchos Teshuvah 2:2 Rambam (Moses Maimonides) explains that a sinner should abandon his sinfulness, drive it from his thoughts and conclude in his heart that he will never do it again.

Isaiah 55:7 Let the wicked forsake his way and the unrighteous man his thoughts: and let him return unto the Lord and he will have mercy upon him; and to our God for he will abundantly pardon.