For me personally I would agree and disagree with you at the same time. I would agree with you that all sickness and injury are not a result of sin. Stuff happens. Where I live in California you have to sign a form when you purchase a house that you are aware that the air here can kill you. You can live a healthy life but you are sucking gunk in all day long.
Where I would disagree with you is that good Christian people have to get sick whether we want to accept it or not. If I can use a crude example I will try and make my point.
People get hit by cars, but you don't have to. If you use wisdom, look, listen, and pay attention you can live your life without ever being hit by a car. Yet there are still those who get hit by cars.
Yes sickness is out there and yes injuries can occur, but what if a person "lived" by faith. Not have faith, but lived by faith. Faith was their lifestyle. When they got up in the morning their faith was active that
Psalms 91 was at work in their life and they were totally protected. What if even though they felt great they had their faith active that if they ate anything, breathed anything, or was around anyone with sickness or disease it would not come them.
Could they prevent injury and sickness in their life. I say yes! It is not a condemnation on those of use who get sick, but an encouragement to believe for the impossible - define the odds - and live a totally completely victorious life in Christ.