I was ambitious and driven, but I felt as if something was missing in my life, and I couldn't explain what it was. My family was from London, but had moved to the US when my two elder brothers and I were very young, so that my father could pursue his career as a surgeon.

We were comfortably middle-class, and it was expected that we, too, would develop highly successful careers, get married and, in turn, have successful children of our own.

My father was an atheist of the Richard Dawkins or Karl Marx ilk, for whom religion was simply a mechanism of political and social oppression. Although my mother never said much to contradict this, she would seem mildly upset when I would occasionally deny the existence of God. I, too, was an atheist. As a teenager, I refused to be confirmed.

Finally, when I was 18, I was able to escape the limitations of suburbia by going to Harvard to read English. I loved it there - studying, writing, and running a modern dance company. I began to discover who I was, and even though I lacked the social confidence that so many of my classmates seemed to have, I started to emerge from my shell bit by bit. I even had a boyfriend - a genuine, lovely guy in the year above me who was heavily into drama. He was a committed Christian, but this didn't cause too many problems, as long as we didn't talk about how we thought each other's beliefs were completely deluded and wrong.

Eventually, the relationship ran its course but, after graduating and landing a job at Carnegie Hall, I began to acknowledge to myself that I no longer found my aggressively atheist take on life adequate. Although I still found it impossible to believe in a god, I gradually became aware that there were other, non-theistic approaches to experiencing the spiritual side of life. I started to do hatha yoga, and was then introduced to Zen meditation by a colleague.

Something clicked, I left my job and returned to England to do postgraduate studies at Oxford. I continued to practise with a local group affiliated to the International Zen Association, which is based in France. Having previously lived such a goal- and achievement-oriented life, sitting in meditation and simply observing my state of being was a new experience. As I examined my ideals, particularly the validation I sought through unrelenting hard work, I found that they were empty; one by one, they dropped away. I realised there were more important things than climbing the career ladder at any cost.

Although it was a liberating experience, it was incredibly frightening at times. I had to reassess my approach to life, and in doing so, acknowledge that, by my previous standards, I felt like a failure. Instead of getting a highly paid job, followed by marriage, a house and children, I was struggling to make ends meet as I cobbled together an existence from undergraduate teaching while trying to finish my doctorate. Then, just as five years of hard work were coming to an end, my supervisors decided that they didn't want to help me with the revisions recommended by my examiners, and I had to move on. Without a doctorate, the academic career I had worked for was impossible. After going through every emotion, and becoming physically ill, I decided to use the teaching experience I'd had at university to go into secondary-school teaching.

I continued to meditate with the Zen group and attend sesshins (retreats) both in the UK and in France. In France, I met a Zen master (a practitioner who has received permission to teach), and under him, I made a formal commitment to follow the Zen path. Unlike in Japan, where Zen monks and nuns are supported by the state, Europeans who make this commitment continue to live and work in society as they did before. For me, the decision to ask for nun ordination came easily. It simply felt like the right thing to do; it made sense. Life was beginning to unfold naturally.

The ceremony took place at my Master's little dojo (meditation hall) near Tours, France, on a beautiful summer morning last year. I received a black kolomo (a kimono with extra-long sleeves) to wear over my white kimono, as well as the black kesa (a rectangular garment that is worn wrapped around the body and over the left shoulder during meditation) and the rakusu (a miniature kesa that is shaped like a short apron) that I had sewn myself. I was given a document that traces my lineage back to Shakyamuni Buddha, a bowl for my meals, and a nun name that will be used only after my death. I cried throughout the ceremony, but the look on my face in the official photograph says it all: sitting next to my Master I look emotional, almost overwhelmed, but relieved and happy.

Nearly a year has passed since then and people's reactions to my ordination have been varied. My mother has been curious and supportive, while my father does not mention it; I have no idea of his opinion, other than that he does not disapprove. I think he sees that I am happier now, which is good enough for him. Because I am now a teacher, I don't shave my head and, as I wear the kolomo and kesa only for meditation, I look no different from anyone else you would see in the street.

When most people hear the word nun, they think of Catholic nuns. Often, their first question is why would I want to give up having sex for ever. Stated in this way, it puts sex on a par with things such as smoking or drinking: self-gratifying acts of pleasurable consumption. If one understands sex according to such a selfish, loveless definition, then I suppose that yes, I have "given it up". One of the vows I made when I was ordained pertains to sex, and it states that you should not use your sexuality in a way that harms. It is not what you do, therefore, but how you do it: using someone as a commodity for one's own satisfaction is definitely harmful if considered in that light. Shortly after my ordination, I met a man with whom I now share a relationship based on mutual trust and respect.

Most of my teenage students know I am a nun, and their reactions fascinate me. They are openly curious about what it means to be a Buddhist as well as a nun and, of course, asking me questions about it is a great time-waster in lessons. One question that comes up fairly frequently is whether I believe in God, but I'm not sure if they understand when I tell them that the idea of the Abrahamic God has no place in Buddhism. At other times, they ask me how I meditate. They put their hands into what they think is a suitably yogic position, shut their eyes, and say: "Ohmmm."

I find their preconceptions entertaining, and they don't want to believe me when I tell them the truth: that we sit still and don't move or make a sound for up to six hours a day. I think it must be fairly strange for them to be faced with someone who has made such a strong religious commitment. Some of them assume I live like a puritan, and are surprised when I tell them that I do drink alcohol and I will eat meat.

While my status as a nun usually fosters a dialogue between me and my students, I sometimes feel it separates us. Nowadays, students think that, to be successful in life, they must strive for high scores, regardless of whether academic learning is right for them. I feel sad at how stressed my students get and, during exams, I remember words from a Zen teacher that to "be adequate" is enough in life.

After I was ordained, my Master told me that in the following year, my karma would move more quickly, and I have found myself making quite a few changes to my life, particularly in terms of my career trajectory. I'm finding the balance, bit by bit. There is a saying that following the Zen Buddhist path is simple, but it is not easy. It takes effort that needs to be renewed daily. When things start to get overwhelming, I just remember the poem that is written in black ink on the white silk that lines my rakusu: "With my kesa and shaved head, I am free." The simple truth of these words will, I hope, always inspire me.