Changing of the mind is the "Heart of Repentance", becoming a pattern of thinking, and a lifestyle.
The First Word of Salvation
Pastor David Frederick teaches the first word of the gospel is "Repentance". It's turning away from sin and toward the Lord. The prophet Zachariah cried out to the people of Israel to repent and return to the Lord: "Turn now from your evil ways and your evil deeds" (Zech. 1:4). Salvation begins with repentance. It involves a change of mind about sin, which leads us to believe in Jesus Christ and brings us forgiveness from God. Yet repentance is more than a once-for-all activity that initiates salvation. It is an ongoing choice - a change of the mind that sees sin as being wrong confesses it and rejects it.
Changing of the mind is the "heart of repentance" becoming a pattern of thinking, and a lifestyle. Romans 12:1-2 Message Bible states, "So here's what I want you to do, God helping you: Take your everyday, ordinary life - Your sleeping, eating, going-to-work, and walking-around life - and place it before God as an offering. Embracing what God does for you is the best thing you can do for him. Don't become so well-adjusted to your culture that you fit into it without even thinking. Instead, fix your attention on God. You'll be changed from the inside out. Readily recognize what He wants from you, and quickly respond to it. Unlike the culture around you, always dragging you down to its level of immaturity, God brings the best out of you, develops well-formed maturity in you". Even though we are secure in Christ, we must continue to see sin through God's eyes and acknowledge it as evil. And when we sin, let's repent, confess our wrongdoing, and receive the forgiveness of God.
An underlying basis or principle :a usually stone or concrete structure that supports a building from underneath. https://www.merriam-webster.com/dictionary/foundation
"Therefore thus says the Lord God, "Behold, I am the one who has laid as a foundation in Zion, a stone, a tested stone, a precious cornerstone, of a sure foundation: 'Whoever believes will not be in haste". Isiah 28:16
Repenting and receiving God's forgiveness through Christ is the beginning of our Salvation. God can not build off our faith without this first step or Foundation laid in our hearts.