Often in our lives, we motivate ourselves by the thought that we only need to get around this corner, and life will settle down. We feel as though peace is within our grasp but we always come up lacking. With each new accomplishment or rite of passage we find ourselves pining for the next. The reality of suffering in this way extends to everything if we really think about it.
Why is this the case?
Well, because our first father plunged us all into a reality that is at enmity with the Triune creator. As the Apostle Paul reminds us in Rom 8:20-24 we, along with the whole creation are aware of, and groan through this reality until by God’s grace we come to the consummation in the regenerated and eternal dwelling place.
When we look at the History of God’s people we see over and over again – what is lacking! 
In 2 Samuel 2:1-4 David is finally anointed and crowned King, but only in Judah. For David to claim his full title as King more need to be done. But even after David is finally King over all Israel the groaning continues, the ‘lacking’ is always evident. David was a man after God’s own heart, but he would die without ever realizing his greatest desires. David is not alone. Abraham, Solomon, you or I, none of us achieve a life consummate peace.
So why rejoice in what’s lacking?
Because it is in what is lacking that the gospel really shines! No one, no matter how rich or well established is free from the groaning torment of Adam’s guilt. Yet God display his love in so many manifold blessings. All with the reminder built in, “this is not your hope!” It is only through faith in Christ that we can look forward to a better place, whose builder and maker is God, where there is really nothing lacking. In Christ we see that fullness. He is the fullness of humanity, the consummation and consummation of all things. Only Christ stops the groaning over what is lacking. Therefore, rejoice in what’s lacking – and let it drive you to Christ.