Changing our nature...what has already occurred within

Why does God insist on making us loveable, lovely, whole?  For certainly he has always loved us, even when we were unlovable; yet this wasn't enough for him, says C.S. Lewis:

"...it is natural for us to wish that God had designed for us a less glorious and less arduous destiny; but then we are wishing not for more love but for less."  - C.S. Lewis, The Problem of Pain

"We may wish, indeed, that we were of so little account to God that He left us alone to follow our natural impulses - that he would give over trying to train us into something so unlike our natural selves:  but once again, we are asking not for more Love, but for less."  -- C.S.  Lewis, The Problem of Pain

I want to answer Lewis here (not knowing how he might respond)...   In order to fashion us into the supernaturally glorious creatures he desires and loves into wholeness, God indeed did change our natural selves, our natural impulses -- from unlovely to noble and good.  This he did at the level of the heart. 

We need not wait for heaven for this.  It has already happened.  It is the promise of Ezekiel 36:26 fulfilled (and in other places throughout Scripture).  We now grow out of that new and noble nature with its noble impulses.  We practice our new nature.  Discipleship is learning how to live from that good heart.