Ezekiel 36:26
A new heart also will I give you, and a new spirit will I put within you: and I will take away the stony heart out of your flesh, and I will give you an heart of flesh.

The heart is where desires come from (Matt 6:21). The new heart is given to us when we are regenerated. We are regenerated when the Holy Spirit comes into our heart. When we are given a new heart, we are given the ability to have Godly desires (Rom 8:5) and the ability to see things from God’s perspective (1 Cor 2:16). Having Godly desires is what it means to have a “heart of flesh”. The heart of flesh is alive and hot as opposed to the stony heart which is which dead and cold. (Rev 3:15).