There's no guarantee that the life of a believer will be without complication or concerns. The person that conveys that message is seriously misinformed.
We then, are called to persevere. Without accepting the situation, we discover ways in which we can serve the Lord with integrity in spite of the malady. The obstruction can take different forms, but we must press on with great resolve.
James 5:11 (MSG)
11 What a gift life is to those who stay the course! You've heard, of course, of Job's staying power, and you know how God brought it all together for him at the end. That's because God cares, cares right down to the last detail.