Shrek: The poses lower to the ground are the most difficult. Arching my back has been hard too.Head stands are actually very easy. I am still intermediate.
Eud: I use to think it was magic and impossible, the truth is, Its all mental. ANYONE can do it ( within reasonable means) if you set your mind to it. This is what I love most about this particular type of Yoga, your challenging your mind and your building a trust with your body. Lots of fear facing. Most importantly,this practice is not limited to good looking young people, ya know? Which unfortunately, you will see a lot of in the media. I admire seeing the older folks over the age of 80 practice. I am a 30 something mom, has't stopped me. I got a lot to look forward to when I get older. ;)
Remember, the only person that holds us back is ourselves. Of course, consult with a physician before any physical activity. This type of yoga may not work for all.
P.S. the man in the green could be a fake, I just thought it was cute lol..