LOL! When in doubt :
-don’t
-modify
-ask for options
-think length, space, comfort versus pain, pinching, bone on bone friction, compression
-get personalized attention
-familiarize yourself with anatomy
-take responsibility
-slow down
-break it down into smaller steps
Patanjali, in the yoga sutras, explained that there are five causes of suffering, one of which is dvesa, aversion, or, revulsion, avoidance. I think this is a larger discussion, involving many personal considerations. Sometimes we avoid things we know will be dangerous, or, we are not ready to do them. At other times, we are just plain afraid, having perhaps imposed limitations which are not really there, we just don’t muster up the courage or right effort. To know what is what for yourself requires healthy introspection and self-reflection. This is a part of yoga practice. Knowing how to balance effort with ease, doing with being, and using intelligence and common sense. Injuries, in the end, do heal and we do learn from all that we do, but they also slow us down, add impediments to health, and create scar tissue. If you can get through practice with safety, I believe you are then enjoying sustainable yoga practice.