(This essay originally appeared on Beliefnet in 2004.)

I first went to an Iyengar Yoga class four years ago. My wife Cynthia had been radiant with enthusiasm every time she'd come back from a class for the previous year and a half. Although she'd never said it, I was aware that she was waiting expectantly for me to try it. She knew I had a lot of resistance, since I had a long history of an almost complete lack of coordination as well as an outstanding ability to space out during physical activities from aerobics to walking (I was famous for walking into the poles for parking signs because I found it difficult to pay attention to anything but my own thoughts).

Cynthia had told me about the belts, wooden blocks, and other props used in Iyengar Yoga in doing asanas (poses or postures), one of the characteristics that differentiates it from other types of hatha yoga, and she'd mentioned that the poses are held longer in Iyengar than in other kinds of yoga. This part made me apprehensive: I was worried about having to hold the poses for more than a brief length of time, but I was also encouraged by the idea of using props because I thought they might make them easier.

I had taken non-Iyengar hatha yoga classes in the past, but all the teachers with whom I'd studied had taught yoga simply as a form of exercise. The poses were to build muscle tone and create flexibility. If the teachers saw the poses within a spiritual context, they didn't share that perspective with us. Consequently, I went to my first Iyengar class just for physical exercise, but I soon realized that Iyengar Yoga offers something greater: It offers what my first Iyengar teacher, Sylvie Terree, calls "food for the spirit."

The class began very differently from any yoga class I'd attended before. We were asked to repeat in unison a Sanskrit chant to Patanjali, the Indian sage who is the father of all yoga. It was voluntary; no one had to do it. There was a handout with the Sanskrit words, their phonetic facsimiles, and a translation. As an ecumenical Jew, I joined the others in repeating the chant.

Also on the handout was a quote from Geeta Iyengar, daughter of the founder, B.K.S. Iyengar, who, with her brother Prashant, has headed the Ramamani Memorial Institute (RMI) in Pune since their father's official retirement in 1984. The quote reads: "We chant so that at the very beginning that feeling of sanctification comes from inside, with the feeling of surrendering oneself, because nothing can be learned in this world unless you have the humility to learn."

I had never before been in a yoga class that felt sanctified, and as we were told to get mats and blocks to work on standing poses, I felt a sense that more was being required of me – and more was being given to me – in this class than I was used to in other classes. I was right. Sylvie demonstrated the poses with a precision that no teacher I had studied with before had. She pointed out the specific muscles we would be using, showed us the alignment for each pose that we would be aiming for, and explained why certain alignments we might be tempted to use would be harmful to our bodies. She talked about the benefits the poses would give us. She also asked each of us if we had any physical conditions she should know about in case she had to modify the poses to accommodate the problem.

As we held each pose, she devoted herself to helping each of us do our best pose. The blocks, I learned, were used by those of us who, like me, have tight legs and shoulders, or have back injuries, because we would throw our bodies into misalignment if we tried, for example, to reach all the way down to the floor with one hand while extending the other arm straight into the air in one of the triangle poses (Parivrtta or Uttihita Trikonasana). Thus, props aren't used to make poses easier, they are used to help us do the poses without forcing ourselves into an approximation of them that might end up doing physical damage. Yoga teaches non-violence; in Iyengar Yoga we learn non-violence within our own bodies and this teaches us non-violence with others.

Of course I didn't learn all of this the first day. That day I learned not only that Iyengar Yoga is precise, but that the precise instructions with which Sylvie taught us the poses – with instructions for our toes and heels, even the skin under our feet, and every part of the body all the way up to our heads – encourages us to bring consciousness to all parts of the body. I learned that precision is displayed in all aspects of the class. We are each responsible for putting away the blocks, mats, blankets, and other props in their proper storage areas. This gives us a sense of responsibility for the practice area, and a sense of connectedness to the other students who will use the props and, by extension, connectedness to all people.

That first day I had my first visual introduction to B.K.S. Iyengar: lining the top of the front wall were photographs of him in the various poses. His mastery of these poses embodies precision – which is why the photos are there. They are instructive and they are also a beacon of inspiration showing us what we are working towards to the best of our individual abilities.

I began going to Sylvie's class once a week. After a year I started to take a second class, with Sue Garfield, whose practice has helped her through severe physical challenges, and whose dedication to practicing Iyengar Yoga as a cancer survivor and also having had cervical spine surgery helped me to see my way to aiming for improvement instead of focusing on limitation. Her commitment was so strong that I became more committed.

I soon found out that Iyengar instructors are very committed indeed. Instead of the one-to-three-month training programs required for beginning level instructors of other types of yoga, Iyengar Yoga requires three years of teacher training to be eligible to take the beginning level certification test. Further training, including studying at the Institute in Pune, is required for more advanced teaching levels, and all Iyengar teachers, regardless of their level, are required to continue studying.

The word that best describes my experience of Iyengar Yoga is integrity. There is an integrity to the way that every class is taught: each Iyengar teacher is there 100% to teach with excellence and to support her or his students. I feel privileged to be in these classes, because I feel the teachers are there as an act of service, that they are there to serve me. The way they serve by teaching me so expertly teaches me another spiritual lesson as I learn yoga: that in my work, in all my interactions, I am there to serve others.

One day, on the Institute's white board, I saw a quote from B.K.S. Iyengar: "If your body can do more and you do not do it, that is unethical practice." That day I added a new level to what Sue was teaching me about the fruits of committed effort in yoga; I began to realize that as hard as I'd been working, my body could do more and my mind could be more focused and aware. I understood as I read these words that Mr. Iyengar was saying that God gives us our bodies and that ethically we must do all we can to make them as healthy as possible. This is the context that Iyengar Yoga provides for practice – taking care of our bodies because they hold the divine spark, the God within us. Indeed, our classes end, as we sit cross legged on the floor, palms together, thumbs against our chest, over our hearts, with our teachers saying "Namaste": "The God in me salutes the God in you," a salutation we then repeat to our teachers.

In my fourth year of Iyengar Yoga, I have noticed that my posture has improved as have my muscle tone and flexibility. Sometimes as I practice my mind actually becomes still, and I practice with the awareness of my body that yoga teaches. Remarkably for someone whose mind has habitually wandered, Iyengar Yoga brings me into the now. This is the intention of the precise instructions in Iyengar Yoga. Working to focus my attention on the different parts of my body involved in the poses makes me shed my preoccupations and cares and concentrate, at least for a time, on the now of practice. Mr. Iyengar talks about this in his book "Light on Yoga": "When the restlessness of the mind, intellect and self is stilled through the practice of Yoga," he says, "The yogi by the grace of the Spirit within himself finds fulfillment." I have had at least an intimation of this, and after every class my mind is refreshed.

I have begun to understand, as I never could have when I went to my first Iyengar class, that for a yogi, fulfillment involves always working. "Work alone is your privilege, never the fruits thereof," Mr. Iyengar writes. "Never let the fruits of action be your motive; and never cease to work. Work in the name of the Lord, abandoning selfish desires. Be not affected by success or failure. This equipoise is called Yoga."

Earlier this year, Time magazine named B.K.S. Iyengar – now 85-years-old and still practicing yoga – one of the most influential people in the world. Also in 2004, the word "Iyengar" debuted in the Oxford English Dictionary.

2004 has been a watershed year for me and Iyengar Yoga, too. For years I was a Level I student and had assumed that I would never move up to Level 2 because it would be too difficult. Lo and behold, with the encouragement of my teachers and my own perseverance, this year I was ready, and I'm now taking at least one Level 2 class in addition to my Level 1 classes each week.

Because yoga is living, it is always changing, always moving. Some days I feel I'm making progress and it's exhilarating, some days I feel frustrated. But when I feel frustrated by what I consider my lack of progress, yoga is teaching me another spiritual lesson: Don't judge; just observe and keep doing the work. As Sylvie says, "Yoga is a lifetime process. There is always something more to learn about yoga, about yourself." That is what keeps it exciting and rewarding, and helps to keep me on the spiritual path.