Like I said, there're not necessarily easy, but my guess--after countless yoga classes--is that for some, those poses are always going to be out of reach. It's not a question of where they are in their practice. For others, they'll be able to do them from day one. From a teacher's standpoint, some poses are worth teaching at all levels because students will never find out if they can do them unless they try. And there's no shame in trying and failing or falling short of some ideal.

I have been regularly practicing for almost 5 years now. I have a fairly strong practice, but regardless of what type of class I go to, there's inevitably at lease one pose that I can't do or can't do as well as I'd like. I spend little time ruminating on whether the pose was appropriate for that level of class or too "advanced." Rather, I merely accept that my body's not capable of that today. I do what I can; that's all any of us can do. Yoga, IMO, is as much about intention and effort as it as actualization and achievement.

If I can't do a particular pose, I either do something else or look around the class as others try it. In some of my advanced classes, we try some CRAZY arm balances, over 50 percent I'm not yet able to do. It's fun and inspiring, though, to watch others as they try.

I'm really not trying to be argumentative here. One of the things I've loved most about my yoga practice, though, is trying/doing things I never thought I could do and that were seemingly well beyond my 40+ year old body. The first time I did a full wheel (basically a backbend), I was utterly shocked. I'd never even been able to do them as a kid. So, I see a huge benefit to trying poses, even as a beginner, that are seemingly difficult. I've also learned that my body is not static. I could do things two years ago that I struggle with today because I was more fit, so my practice is a moving target. I like to allow enough room in my practice to be both surprised by, and forgiving with, my body.