The first step in Spirit-filled health is to acknowledge that, no matter what you do, at the end of the day God is in control.
If God designs sickness or injury into your life to test you, teach you, grow you; then that will happen no matter how disciplined your diet and exercise.
That doesn't mean that you shouldn't be a faithful steward of your own body, gifted to you by God. You have worth as a being who is created in the image of your Maker. Honour God in this and He will honour you.