Salvation changes our heredity

I was reading "My Utmost for His Highest" this afternoon, and was struck by this quote:

"The great wonder of Jesus Christ's salvation is that He changes our heredity. He does not change human nature - He changes its source, and thereby it's motives as well"

I'm not sure why I'm just getting this. I cannot be Christlike through my own will and power. I have to allow Jesus to change me from the inside, change my character, motivations, thoughts, emotions, everything. Otherwise, no matter how hard I try, it's just me. Not Christ.

I enjoyed reading Matthew 5 (The Message) that went along with the devotional:

"You are blessed when you're at the end of your rope. With less of you there is more of God and His rule.
You're blessed when you feel you've lost what is most dear to you. Only then can you be embraced by the One most dear to you.
You're blessed when you're content with just who you are - no more, no less. That's the moment you find yourself proud owners of everything that can't be bought.
... You're blessed when you can show people how to cooperate instead of compete or fight. That's when you discover who you really are, and your place in God's family."