The world is not a perfect place, it is so ultimately because of the foolish choices of man. God created an idyllic world for man which man rejected, leading us into a world with many problems. Life can be cruel and unfair, yet it can also be rewarding and full of many blessings given by God. It is the uncertainty of the future or sometimes even the day that can cause us to stress about what will come.
In life perhaps there is nothing man understands paradoxically both better and less than sin. Man is familiar with what sin offers in the form of temporal pleasure, seemingly positive temporal benefits, etc. in a legion of ways, going so far as to actually create new and evermore depraved ways to engage in sin. Man knows sin intimately by encouraging its practice and showing wholehearted approval to its furtherance (Rom. 1:32).
The Book of Job tells a difficult story which involves great loss and hardship, and the choice to trust in God no matter what. The calamities that befall Job after Satan is allowed by God to harm him are truly devastating. Job first loses his livestock, which were both his livelihood and his fortune. He then loses all of his children, which were his true treasure and hope for the future. He finally loses much of his health, left in a miserable and painful state covered in boils.
In the physical body, the nervous system serves an important purpose in transmitting signals from the brain in order to control muscles and other parts of the body. The nervous system also serves the purpose of warning the brain of possible problems throughout the body through the signal of pain.