From an upcoming, much longer post, detailing my second visit to The Washington University in St. Louis. Where I took a course by Shirley Sahrmann and the physical therapy department. You can read about my first visit here.
Your knee has been hurting a while. You get some X-Rays; the doctor comes back and states you have pain due to osteoarthritis.
This statement by Shirley: “Arthritis is a normal response to an abnormal stimulus,” is saying something profoundly different. You have arthritis in your knee due to something else. That something else? How you’re moving.
Say you had a meniscal tear in your right knee. Because of this tear you have some instability. Or, you suffered the tear because of instability. Either way, you have issues at your knee.
In the context of the “movement system,” instability means your knee is moving too much in a particular direction. It’s hypermobile. Like someone whose knee caves in too much, too often. The body doesn’t like this. It’s equilibrium has been thrown off. What does it do? It tries to stabilize things of course. How can it do this? Arthritis.
What’s one way to block movement? Put some bone in front of it. What does arthritis do? Lay down extra bone. The body uses arthritis as a method to hopefully change how the knee is moving. It’s trying to make the knee LESS mobile. This is a reversal of conventional medicine, which tells us “You have arthritis, now you have pain.” Shirley’s statement is saying, “You had some issue before, now you have arthritis.” This is crucial because it dictates the treatment. You don’t go trying to get rid of the arthritis in the hopes that solves the issue.  You solve the issue in the hopes your body stops needing to generate arthritis!
Another example: If someone has lower back pain long enough what happens? The disc(s) atrophy, then the body lays down bone, such as spurs, and eventually the spine may fuse. Where does it fuse? At exactly the location the person is moving too much!
The body knows what’s wrong. If you don’t correct things by changing how you move, the body will eventually force you to move differently. It’s like when people drink too much. If you don’t stop drinking, the body will make you. It will make you black out, it will make you pass out, it will make you vomit, it will make you feel like a bomb went off in your head, it will make you forever hate the smell of a certain type of liquor, whatever it has to do in the hopes you’ll adjust your drinking. It’s trying to help you. It’s trying to make sure you don’t poison and kill yourself.
More specifically: If you don’t stabilize your spine, your body will do it for you. This is why you rarely see people with lower back pain their entire lives. At some point it goes away because the body will handle things on its own.
It’s so rare the body doesn’t have a legitimate reason for what it’s doing. We all know the 10 year old who gets cancer with no apparent explanation, but this is the (extreme) outlier. The body doesn’t just do crap to hurt you. It doesn’t just lay down new bone to piss you off. It’s doing it for a reason. A reason almost always to your benefit.
Stop saying “Your body is a piece of shit,” “My body sucks,” “My body hates me.” It’s telling you something. You need to figure out what. The body is doing its part; you need to do yours. I’d wager in even the extreme outliers, the body is doing something for our benefit, we just don’t know how or why. 
Is the body always right? Is it always doing things perfectly? Of course not. But people say with age you gain wisdom. Think about how long the human body has been around, how much it’s gone through, how much it’s seen…It has quite a bit of wisdom.
 I discuss how getting rid of arthritis in the knee doesn’t alleviate pain in this post: Should you have surgery for arthritis in your knees?
 An example of one outlier, where many chalk it up to “a shitty hand”: There is a great book called Survival of the Sickest by Sharon Moalem. Per the title, the book looks at why people who get sick are still in the gene pool. Shouldn’t they have been weeded out by now? There’s no good in having a disease. Why on earth would someone get something like Type 1 diabetes?
First, if a disease doesn’t preclude you from reaching a point in which you can reproduce, it can be passed on. We could all have a disease that kills us by 30, but if we reproduce before 30 years old, our kids can inherit the disease.
Second, and this is where the book gets trippy, maybe these diseases are why some of us are here to begin with? Maybe, without Type 1 diabetes being in your gene pool, you would have never made it here? Type 1 diabetes is…beneficial?
One of the symptoms of Type 1 diabetics is a lack of insulin production, leading to excessive sugar in the blood. Another symptom is frequent urination. As a Type 1 diabetic you’re likely to 1) Have less water in your body than someone else and 2) Have more sugar in your body than someone else.
Moalem covers how we’ve found a good deal of Type 1 diabetics appear to have heritage tied to surviving extremely cold weather. If you’re a Type 1 diabetic in an ice age, you possibly have less water in your body due to your more than normal urination. Less water in your body = less substance in your body which can freeze and kill you.
Next, the excess sugar in your body can help act as an antifreeze. Moalem references how grapes which survive colder weather do the same thing i.e. have increased amounts of sugar. This is well documented because these grapes end up sweeter. (They’re popular in the wine community.) The plethora of sugar in a slurpee is a good example too. Think about the ice in a slurpee versus a cup of water. Shriveled, soft ice compared to solid, hard ice. Soft ice is a lot less damaging than hard ice. Plus, it warms faster. Say you’re a grape with some ice crystals inside you from cold weather. If you have more sugar inside you, that ice can be made softer, thus warm faster. The faster you can warm yourself up, the better.
So, while Type 1 diabetes may, in certain circumstances, make it so you don’t live as long as a normal person, it at least gets you to an age you can reproduce. An age you may not have gotten to without the disease (you would have died in the ice age). Thus, Type 1 diabetics are still around.
The book has more examples. Lord knows how many ailments fit in this category.