Yoga means "yoke." The idea is that the postures, the asanas, integrate the body and not-body parts of ourselves. I say not-body, instead of spirit, mind, or soul, because we don't know what any of the not-body existence really is. We just know it is there. And that it needs to be yoked to the body.
When we get what we want, the body goes one way and the not-body goes the other way, into their own rooms, as it were, to eat from dinner trays and watch their own choice of cable fare.
When we are afraid, suddenly the body and not-body are very interested in each other, both for what they can do for each other, and for more sentimental reasons.
When I sit in Calculus class and can anticipate where the professor is going with the demonstration of, for instance, instantaneous rate of change, my mind wanders off. My body sits in the miserable little desk, and tries to communicate with the outside world through gurgles and twitches.
If the professor suddenly is writing rational functions, i.e. f(x) = 1-(1/x) on the board, fear seizes me. I missed many points on that section in pre-calc. It makes me sweat and tremble. My mind goes blank. I want my mother.
At the moment of greatest fear, my body and not-body are perfectly superimposed, like siblings separated for years and suddenly running into each other in the produce section of the grocers. "Hey!" "Hey, you are looking good!" "Are you still living in Bloomington?" "Looks like we went to the same barbershop." The chitchat masks the great relief, curiosity, and uneasiness occasioned by such chance but profound meetings.
From the back of the mind, the supervisor tells the mind to start taking notes and the body to quit interrupting. The brief moment of rapproachment between body and not-body is over, but it has done its job. For some time afterwards, a melody runs through the chambers of the self, through the shallow blood streams and across the fields of wild identity flowers in bloom. The melody is simple and heartbreaking. When you hear it, you are one. When you don't hear it, you don't know you ever heard it.
No one chooses fear. It is easier to suffer.