Tonight in my yoga class Baxter made a good point. You shouldn’t be doing anything that creates pain. But challenge is OK. He said for him he usually knows the difference by checking on his breathing. If you are having a difficult time breathing or holding your breath it probably means you need to find your edge and take a step back.
I think that is a great way to approach any type of exercise. But that is one of the many things I love about yoga. There is no competition; no attitude about no pain, no gain; no going beyond what you are capable of; finding your edge and taking a step back.