Physical Danger
If you don't know what you're doing, yoga can actually do severe damage to your body. Every year thousands of yogi wannabes who think they're human pretzels decide to push through the pain, only to throw out their backs or screw up their wrists (source).
You'd think yoga teachers would know better than to make those rookie mistakes, and for the most part they do take precautions. But when it's your job, you can't just sit it out for every ache and pain. You either play through it or say goodbye to that week's paycheck. If you do the former, you'll end up with a hip replacement by fifty.
That said, yogis also report lower blood pressure, cholesterol, and levels of depression than the rest of us mere mortals. And no one's shooting at you, trying to blow you up, or even just operating heavy machinery in close proximity. So practice smart and you'll make it out with your (crazy-flexible) limbs intact.