Solomon referred to envy as a "rottenness of the bones," (Proverbs 14:30) a disease which consumes us from the inside out. Other emotions such as guilt, worry, and anger act the same way, inevitably producing symptoms and diseases such as cancer, heart conditions, and other physical problems.
One of the most widespread of these negative emotions is unforgiveness; the inability to effectively deal with the past. The stress from unforgiveness affects not only our relationships, but also the very essence of our lives, effectively killing us and smothering our joy.
Most of our physical problems have spiritual root causes which can be readily discovered and addressed. Treating only the physical symptom is like painting over rust; the original basis for the disease remains, and it may eventually allow the disease to return. Many of our Health issues are amplified by sadness as well.
Think about this: could God use a disease in the physical body, which lasts only for a few years, to draw our attention to a disease in our spiritual body, which lasts forever? He surely could, and does. But allowing our physical body to be healed without attending to the higher priority of our spirit could remove the motivation to address the spititual condition, so God usually institutes a "Healing Plan."
A program of healing prayer usually works out more like this:
1. God takes the first step and quickly improves the physical condition.
2. Improvement slows down until the prayee addresses possible spiritual conditions.
3. Improvement accelerates, then may hit another "spititual plateau," and the 1-2 cycle repeats.
God can also instantly take a person from "sick" to "healed," a process He's just as good at today as He was 2000 years ago.
Of course, the optimum situation is to examine ourselves for needed spiritual cleansing and growth while we are still healthy, but we have to begin where we are at: here and now. He is also an expert at turning sadness into JOY!