For many years, I practised yoga regularly (a regular practice for me back then was anything from once a month to once a week!); I was content to stay within the confines of what I knew in fact I used to be one of those students in the class who would gawk when the teacher mentioned arm balances...to be honest I just didn't see the point and certainly didn't feel like I could master one anyway - I could seem to get one foot off the floor but never both at the same time.
I reached a point in my life where I knew I was capable of more and I desperately wanted to emulate this is my asana practice but wasn't really sure where to begin. Arm balances didn't seem the obvious choice at first, especially given that I have had a dodgy wrist since my teen years and a shoulder injury on the same arm!
In terms of fear factor - they were definitely the preferred option to inversions - I certainly wasn't ready to get upside down but I what I did need was a challenge. When I set myself the task of learning astavakrasana (8 angle pose) - I practiced a sequence of deep hip openers over a period of time and included some basic some shoulder strengthening as well. One afternoon I put it all together and wasn't prepared for what happened next...I was flying...I felt strong, elegant and oh so capable. It was a HUGE buzz! Thus began a love affair with arm balances.
The myth with balancing on hands and arms is that a lot of upper body strength is required, and while some is certainly useful, it's really a balance of strength, flexibility and knowing how to leverage your body accordingly. In most postures the legs are positioned differently on the arms and or the shoulders - and knowing how, why and where to place the legs to create a strong relationship between the upper and lower body removing the 'mystique' of the posture to make it accessible.
Prepartory postures to help build strength are chatarunga dandanasana, navasana as well as adho mukha svanasana (downward dog). It's rare that you'll see an entire class dedicated to arm balancing because of the energy required to do them, so they're usually limited to a select few in each class! Ultimately, this family of postures are exhilarting and kind of addictive...at the same time however, they keep you humble and remind you that there is so much more to learn...both on and off the yoga mat!
PS I've included a photo of that afternoon when I did my first astavak...a proud moment!