Jeremiah 31

Jeremiah revealed of our day -

"Behold, the days come, saith the LORD, that I will make a new covenant with the house of Israel, and with the house of Judah:
32 Not according to the covenant that I made with their fathers in the day that I took them by the hand to bring them out of the land of Egypt; which my covenant they brake, although I was an husband unto them, saith the LORD..." (Old Testament | Jeremiah 31:31 - 32)

It becomes clear that the Lord will establish again in the latter days, a "new and everlasting covenant" and -

"...this shall be the covenant that I will make with the house of Israel; After those days, saith the LORD, I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people." (Old Testament | Jeremiah 31:33)

I note that we will not write this covenant and His law in our hearts, but He will put and write this law in our hearts, much like the the people of Alma where -

"...he changed their hearts; yea, he awakened them out of a deep sleep, and they awoke unto God." Book of Mormon | Alma 5:7)

As we choose to accept and enter into His new and everlasting covenant, It is His Spirit that actually changes our hearts.