As man is united to God physically, his actions begin to change. There is an observable difference in who he was and who he is becoming. As man is united to God spiritually, he begins to reflect the light of God into the world. His spirit houses the very light of God and is shown to those around him, as Jesus said, "You are the light of the world. A city set on a hill cannot be hidden." As man continues investing in the divine nature he begins to bear God's fruit. As when man and wife cleave to one another in a marriage ceremony there life begins to form around one another, so when man is united to God his inner and outer life are formed around the divine nature. As kind cleaves to kind, human to human, so mankind created in the image of God cleaves to God.
As anyone who has ever married another can attest, cleaving and becoming one flesh is not a simple task. There is work involved. True relationship involves un-learning and re-learning. And as a marriage grows, each spouse begins to learn the things that bring pleasure to their partner. They begin to learn how their partner communicates, the rhythms of their life, what they are passionate about, etc... As they learn about their other they (hopefully) begin to accommodate what they have learned and uplift the individual. In this accommodation, their lives are knit together.
When Adam and Eve were "born of God" they immediately went about doing what God had been doing:
“Then God blessed them, and God said to them, ‘Be fruitful and multiply; fill the earth and subdue it; have dominion over the fish of the sea, over the birds of the air, and over every living thing that moves on the earth.’” Genesis 1:28
God had just subdued creation by bringing order out of a dark, shapeless void. He then filled creation with land, sea, and life. Adam and Eve, born of God, were united in will to God. In fact, they never even needed to ask God what to do. When your will is united with his, it is not a matter of discovering what to do, it is a matter of becoming who he created you to be.
When Jesus stated the fatherhood of the Pharisees, he made something clear:
“You are of your father the devil, and your will is to do your father's desires...” John 8:44
The thing you are born of you act on. Your family dynamic will help determine the way you act. The Pharisees had more in common with the deception of the serpent. When Adam and Eve disobeyed God and bought into the deception of the serpent, they were "of their father the devil." They had just acted according to another's parentage.
Being born of God means you would do the kind of things that God desires. Your union with God finds its outworking in your will. The first action of man in relation to God was to respond to his will, and the first action of man in response to another was to cleave. In this we have a picture of the divine union.
Maximus the Confessor, an early church theologian, states that being born of water (John 3:5) “bestows the grace of adoption, which is entirely present in potency in those who are born of God,” and being born of Spirit is “wholly by active exertion, that grace which deliberately reorients the entire free choice of the one being born of God towards the God who gives birth.”
In other words, our born again experience is twofold. The first is the potency of grace bestowed at adoption, or the power of grace is made available to the new believer. The second is the active engagement with that grace, whose singular purpose is to pull you towards the one who granted spiritual birth in the first place. It is your free will gravitating towards the will of God.
Just as in cleaving, being born of water and Spirit is intended to change everything about you. When Jesus demonstrated this life of the Spirit, he showed us the highest form of life imaginable. The ultimate expression of the life and will of God in the individual is that you would give your life for others.