Ahhh, the injuries. You're less likely to meet an Ashtangi who hasn't gone through any type of aches or pains than meet an Asian from a middle-income family who hasn't played either the violin or the piano in his/her lifetime.
And I'm not talking about injuries that occurred due to an inexperienced teacher who might have adjusted you poorly or too strongly. I'm talking about the injuries that just happen because of something you do...to yourself. It's bound to happen when you're keeping a daily practice, where most of the time you're not even fully awake yet.
And did I mention the caturangas? We do something like 60-70 of them in a 1.5 hr practice. Talk about our wrists and shoulders!
I think most of the injuries happen when we come out of an asana. In a typical yoga class, the teacher gives a lot of details and care in how to safely enter and breathe through an asana, but rarely does he/she instruct on the proper ways of exiting. These habits are reflected in our own practice. We take time to set ourselves up, and remembering to breathe while we are in the pose, the body in all its great integrity. Then all of a sudden--SNAP--we're out of the asana. We lose everything. We lose the stability of the posture and we lose the breath. Our mind is already on the next asana before we even safely exited the current one. Where's that "be in the present" spirit?
However, our own injuries can be very good teachers. Going through an injury is a humbling experience. "Pain is real"...it brings you back down out of cloud 9 from your extreme backbending or legs knotting over the head. As David said in the video below (2 min mark):"...that being hurt is what actually brings you to a place of honesty, of realness within yourself."
You have to learn how to modify, and modify, and modify some more. You try not to gaze at the perfectly flat pascimottanasana next mat over as you focus on your own bent-knees, navel-barely-touching-the-thighs forward bend. On some days you might have to practice through gritted teeth, even with all the modifications you are doing already. In sum, you take on a beginner's perspective on the physical practice.
Eventually, you begin to trace back to the source, the asana or the sequences of asanas that might have triggered the injury. You learn from what you might have done and correct it, or you discover the weaker areas in your body and learn to strengthen them. You begin to look at certain asanas in a new light and uncover the true mechanics behind them. With this new knowledge and humbleness, your body begins to repair and renew itself into a better, stronger body. You ultimately become a better teacher to yourself and to others.
A good teacher is one that can empathize with the students. My experiences with my own injuries allow me to guide my students out of similar situations and help them create safer practices. Injuries aren't always a curse. When you learn how to battle through them, you emerge with a stronger body and an enhanced awareness, then they become blessings.
As Pattabhi Jois said: "New body is making!"