This is one of the major questions that we as Christians need to be ready to answer. It's one that most of us don't really ever think about, at least if you grew up in the church like I did. When bad things happen to us, somebody simply says, it's God's will, don't worry about it anymore.
I have been reading a book by Steven James called "Story". In this book, James states his premise that most of us have been exposed to the crucifixion story so much that we have become callous to it. However, he compares our experience with the story of the crucifixion to coming into a movie during the climax and ending. We know how the story ends, but we don't know all the details from the rest of the story that make it so meaningful. In his book, James' goal is to expose the reader to the whole story, the beginning, the body, the climax, and the ending.
In his discussion of the fall of man, he points out how God intended our lives to be. Perfect interaction with God is what we were destined for. Then sin entered the picture and several relationships were broken. James calls the imperfect characteristics of our world thorns and this is what he says, "The thorns weren't a bully-God's way of getting back at those who wouldn't listen to him, they were simply a reminder of who we are. Their prick reminds us who we became on that day when our first parents charted a course away from God and shipwrecked us here on this imperfect island of The Way Things Are."
These thorns hurt, thorns like cancer, old age, bad relationships, shattered dreams, broken trust, but they also remind us that we still have a rose. Isn't that a beautiful thought! These thorns remind us that we have a rose and there is hope for the future. The thorns remind us that we need God and he loves us. If there were no thorns, then why would we strive for a place without them? And if there were no thorns, we would know that God does not really care for us because all he would be is a facilitator to put us on earth to live life, and then to die, never really desiring to seek something better.
We have seen those moments in life that are absolute harmony. God allows those moments to let us desire that harmony all the time. Just remember, when things are going horribly, and it seems like there is no light at the end of the tunnel, there is a rose that is attached to the thorns and it gives us hope.