Heart Change Wrought by the Holy Spirit
And I will give you a new heart, and a new spirit I will put within you. And I will remove the heart of stone from your flesh and give you a heart of flesh.
He saved us, not because of works done by us in righteousness, but according to his own mercy, by the washing of regeneration and renewal of the Holy Spirit,  whom he poured out on us richly through Jesus Christ our Savior,
Regeneration is a change wrought by the Holy Spirit in the heart of a person transforming their motivation from a heart of self-centeredness to a will that is Christ-loving and people-serving. This work of regeneration is released by faith and changes us from hearts of stone, that can only sin, and nothing else, to hearts that serve, love, and sacrifice.
This means that our regeneration is owing to the historical work of Christ. . . . New birth is not a vague spiritual change disconnected from history. It is an objective historical act of the Spirit of God connecting us by faith to the historical, incarnate—the appearing—Lord Jesus, so that the life he now has as the crucified and risen Savior has become our life because we are united to him. New birth happens because Jesus came into the world as the kindness and love of God and died for sins and rose again.
John Piper, Finally Alive: What Happens When We Are Born Again (Christian Focus, 2009), 94.