These obstacles are disease, inertia, doubt, heedlessness, laziness, indiscipline of the senses, erroneous views, lack of perseverance, and backsliding.

Iyengar breaks down these nine obstacles into four groups:
Physical – disease, inertia
Mental – doubt, heedlessness, laziness, indiscipline of the senses
Intellectual – erroneous views
Spiritual – lack of perseverance, backsliding

Physical

One of my favorite phrases is You can’t teach a starving man to meditate.  I feel like disease falls under this concept.  In yoga you need to know your body and accept it.  Faced with the entropy of daily life, it takes time to determine the difference between aches and ailments.  When I started Iyengar yoga I suffered from chronic pain.  Over time, I discovered that most of the pain I experience is derived from stress.  Yoga gifted me self-awareness which reduced my stress and consequently I feel less pain.  However, if I have a kidney stone no amount of yoga will treat it.  Doing yoga allows me time to reflect on how I feel and know when I need treatment versus time.  It feels great to know the difference.

Inertia is a bigger obstacle in my world.  The sanskrit word styana is also defined as mental laziness and lack of interest.  When I’m depressed it feels like there are huge ruts along my path that take special effort to avoid.  I can get trapped at home by my social anxiety or worse, driven to drink by my insecurity.  My interest in things I love wanes when I get caught up in the bustle of responsibility.  I start to slide down a slippery slope of procrastination and before I know it all of my free time feels weighed down by my sluggish ambition.  I half-heartedly write or absent-mindedly do yoga poses.  Slowly, I’m thrown off balance and before I know it time is moving too fast.  The only solution I’ve found is seeking out fuel and putting the motion back into my ocean.

Mental