There are two principles at work in the world. One is the principle of the law. Scripture says God gave the law, but it wasn't intended that we should live by it. We cannot live by the law. We are not able to keep it.
God created the world perfect. But sin entered and contaminated the world; it broke our hearts. When we were born, our hearts existed in a condition that was against God. Our hearts were filled by sinful desires. And the law actually encouraged those desire. So, we sinned.
If we live with the focus to obey God's law, we will fail. This is why God insituted the second principle.
The second is the principle of the Spirit. We give allegiance to Jesus, and God sends his Spirit into our hearts. The Spirit begins to create our hearts anew. The Spirit makes our motivations and want-to's brand new.
Living by want-to has a greater and different power than living by have-to. Which is why God works in our hearts, changing our want-to's.