While this guidance may be applicable to some people working in other areas, the examples I will use all come from journalism, as most of those writing to me want to be journalists, and this is the field in which I have mostly worked. Before you take it, I should warn you not to rely on my word alone. I can't guarantee that this approach will work for you. You should take advice from as many people as you can. Ultimately, you must make your own decisions: don't allow me or anyone else to make them for you.

The first advice I would offer is this: be wary of following the careers advice your college gives you. In journalism school, for example, students are routinely instructed that, though they may wish to write about development issues in Latin America, in order to achieve the necessary qualifications and experience they must first spend at least three years working for a local newspaper, before seeking work for a national newspaper, before attempting to find a niche which brings them somewhere near the field they want to enter. You are told to travel, in other words, in precisely the opposite direction to the one you want to take. You want to go to Latin America? Then first you must go to Nuneaton. You want to write about the Zapatistas? Then first you must learn how to turn corporate press releases into "news". You want to be free? Then first you must learn to be captive.

The advisers say that a career path like this is essential if you don't want to fall into the "trap" of specialisation: that is to say, if you want to be flexible enough to respond to the changing demands of the employment market. But the truth is that by following the path they suggest, you are becoming a specialist: a specialist in the moronic recycling of what the rich and powerful deem to be news. And after a few years of that, you are good for very little else.

This career path, in other words, is counter-educational. It teaches you to do what you don't want to do, to be what you don't want to be. It is an exceptional person who emerges from this process with her aims and ideals intact. Indeed it is an exceptional person who emerges from this process at all. What the corporate or institutional world wants you to do is the complete opposite of what you want to do. It wants a reliable tool, someone who can think, but not for herself: who can think instead for the institution. You can do what you believe only if that belief happens to coincide with the aims of the corporation, not just once, but consistently, across the years (it is a source of wonder to me how many people's beliefs just happen to match the demands of institutional power, however those demands may twist and turn, after they've been in the company for a year or two).

Even intelligent, purposeful people almost immediately lose their way in such worlds. They become so busy meeting the needs of their employers and surviving in the hostile world into which they have been thrust that they have no time or energy left to develop the career path they really wanted to follow. And you have to develop it: it simply will not happen by itself. The idea, so often voiced by new recruits who are uncomfortable with the choice they have made, that they can reform the institution they join from within, so that it reflects their own beliefs and moral codes, is simply laughable. For all the recent guff about "corporate social responsibility", corporations respond to the market and to the demands of their shareholders, not to the consciences of their employees. Even the chief executive can make a difference only at the margins: the moment her conscience interferes with the non-negotiable purpose of her company - turning a profit and boosting the value of its shares - she's out.

This is not to say that there are no opportunities to follow your beliefs within the institutional world. There are a few, though generally out of the mainstream: specialist programmes and magazines, some sections of particular newspapers, small production companies whose bosses have retained their standards. Jobs in places like this are rare, but if you find one, pursue it with energy and persistance. If, having secured it, you find that it is not what it seemed, or if you find you are being consistently pulled away from what you want to do, have no hesitation in bailing out.

Nor does this mean that you shouldn't take "work experience" in the institutions whose worldview you do not accept if it's available, and where there are essential skills you feel you can learn at their expense. But you must retain absolute clarity about the limits of this exercise, and you must leave the moment you've learnt what you need to learn (usually after just a few months) and the firm starts taking more from you than you are taking from it. How many times have I heard students about to start work for a corporation claim that they will spend just two or three years earning the money they need, then leave and pursue the career of their choice? How many times have I caught up with those people several years later, to discover that they have acquired a lifestyle, a car and a mortgage to match their salary, and that their initial ideals have faded to the haziest of memories, which they now dismiss as a post-adolescent fantasy? How many times have I watched free people give up their freedom?

So my second piece of career advice echoes the political advice offered by Benjamin Franklin: whenever you are faced with a choice between liberty and security, choose liberty. Otherwise you will end up with neither. People who sell their souls for the promise of a secure job and a secure salary are spat out as soon as they become dispensable. The more loyal to an institution you are, the more exploitable, and ultimately expendable, you become.

None of this, of course, means that you can start doing precisely what you want to do straight away, and be remunerated as you might wish. But there are three possible approaches I would recommend.

The first is simply to start how you mean to go on. This is unlikely, for a while, to be self-financing, so you may need to supplement it with work which raises sufficient money to keep you alive but doesn't demand too much mental energy. If you want to write about the Zapatistas in Mexico, earn the money required to get you out there and start covering them. If you want to make it pay, you must be enterprising. You should investigate all the potential outlets for the stories you hope to come across: magazines, newspapers, radio and TV stations, websites and publishers.

You should have a clear view of what you want to cover before you go, plan it carefully and find as many contacts as you can from among people with some knowledge of the issue. But at the same time you should be ready for stories you don't anticipate, which might find a home somewhere unexpected. You might for instance come across a wildlife story while you're there, with which you could help finance your trip by writing it up for a wildlife magazine. You might supplement your earnings with a travel piece, or something for an architectural magazine or a food programme. Editors are sometimes delighted to receive material from outside the box (though more often they simply won't understand it). Work in as many media as you can, and be persistent.

Be prepared to live and travel as cheaply as possible: for my first four years as a freelancer I lived on an average of five thousand pounds a year. In seven years working in the poor world, I managed to keep my expenses down to three thousand pounds a year. This is a good discipline for any freelancer, however well you're doing. If you can live on five thousand pounds a year, you are six times as secure as someone who needs thirty thousand to get by. In Britain, however, the possibilities of thrifty living have now been clouded somewhat by student loans: many people looking for work are already burdened by debt.

Work hard, but don't rush. Build up your reputation slowly and steadily. And specialisation, for all they tell you at journalism school, is, if you use it intelligently, not the trap but the key to escaping from the trap. You can become the person editors think of when they need someone to cover a particular issue from a particular angle (that is to say, your angle). They then respond to your worldview, rather than you having to respond to theirs. It's surprising how quickly you can become an "expert" in a particular field: simply because so few other journalists will know anything about it. You will find opportunities, and opportunities will find you.

The second possible approach is this: if the market for the kind of work you want to do looks, at first, impenetrable, then engage in the issue by different means. If you want to write about homelessness, for example (one of the great undercovered issues of developed societies), it might be easier to find work with a group trying to assist the homeless. Learn the trade by learning the issues, and gradually branch into journalism. Though this takes you a step or two away from your ideal, at least you will be working with the people experiencing the issues which interest you, rather than with the detached men and women in the corporate newsrooms who have themselves lost their dreams, and who know as little about the real world as the careers advisors who helped land them in those jobs in the first place.

The third approach is tougher, but just as valid. It is followed by people who have recognised the limitations of any form of engagement with mainstream employers, and who have created their own outlets for their work. Most countries have a number of small alternative papers and broadcasters, run voluntarily by people making their living by other means: part time jobs, grants or social security. These are, on the whole, people of tremendous courage and determination, who have placed their beliefs firmly ahead of their comforts. To work with them can be a great privilege and inspiration, for the simple reason that they - and, by implication, you - are free while others are not. All the money, all the prestige in the world will never make up for the loss of your freedom.

So my final piece of advice is this: when faced with the choice between engaging with reality or engaging with what Erich Fromm calls the "necrophiliac" world of wealth and power, choose life, whatever the apparent costs may be. Your peers might at first look down on you: poor Nina, she's twenty-six and she still doesn't own a car. But those who have put wealth and power above life are living in the world of death, in which the living put their tombstones - their framed certificates signifying acceptance to that world - upon their walls. Remember that even the editor of the Times, for all his income and prestige, is still a functionary, who must still take orders from his boss. He has less freedom than we do, and being the editor of the Times is as good as it gets.

You know you have only one life. You know it is a precious, extraordinary, unrepeatable thing: the product of billions of years of serendipity and evolution. So why waste it by handing it over to the living dead?

by George Monbiot

What lessons could you take from George's story to use in your own career change? Let us know in the comments below.