The greatest obstacle to the practice is one's own prejudices based on one's own preferences.
There is a riddle that goes like this: A father and son got into a serious car accident and were taken to the hospital. The father got operated on right away. The surgeon took one look at the son and said "I cannot operate on him. He's my son." What's the story?
Out of the 8 classes that I taught this week, only one person in one class was able to solve the riddle. The surgeon is a woman and she is the mother of the son in the car accident. It's interesting how our prejudices can be very subtle and well-hidden. Most of us don't genuinely believe that women are not capable to be surgeons, and yet it doesn't immediately occur to us either that the surgeon in the riddle is a woman, or that she could be a mother. Our prejudices can be very casual and deep-seated, such that it does not immediately surface unless examined.
All of us are products of our society. What we see, what we hear, what we experience influence the way in which we perceive the world. Today, the world is plagued with prejudices ranging from sexism to heterosexism to classism to racism to speciesism. In all of these prejudices, the mistaken notion is that one group of beings is superior to another group of beings. This thinking is an obstacle to our yoga practice in that if we believe others to be "less", we cannot truly feel they are a part of us, and as long as we create this divide, this separation will hold us back from a state of yoga.
To let go of our prejudices, we do not necessarily have to become experts in knowing the "others" inside out. We can simply begin by wishing for their happiness. When we offer our actions with the intent of bringing happiness to others, we understand that their happiness does not take away from our happiness. The opposite is in fact true. When our intent and actions bring happiness to others, we get that happiness in return, and we are freed by it.
Hanam esam klesavad uktam. Any being, regardless of form or shape, religion or belief, race or species, deserve to be happy and free. May we have the courage to confront our prejudices so that we can free others from the bondage of our limited perception, and we can then free ourselves from the burden of separation.