In the 1979 movie Porridge, set within the walls of Slade Prison, a charity football game has been arranged between convicts and celebrities as part of an elaborate escape plan. During the game the rather meek warder, Mr Barraclough, acts as linesman and when the ball goes out for a throw-in he awards it to the celebrities. As is often the case in football games, one of the opposition players disputes the linesman's judgement. After questioning Mr Barraclough's eyesight, the prison player informs the linesman that the ball had come off the celebrity player before going out. "Oh, did it? Sorry," says Barraclough, holding the flag up in his other hand and awarding the throw to the prisoners. The celebrity contests this and the hapless linesman reverts to his original decision and the whole episode breaks down into chaos.

This scene shows quite graphically that old adage that you cannot please all of the people all of the time. What Mr Barraclough lacked was assertiveness, the confidence to stand by his decision and to say no. As funny as this scene is, away from the big screen a lack of assertiveness can be anything but a laughing matter.

For all it consists of only two letters, the word 'no' is sometimes the most difficult to say. Many people give in to unreasonable demands made of them because they feel that a refusal would portray them as unwilling to help the cause or just plain rude. 'Caving in' to the demands of others can be the first step on a slippery slope, as word of a soft touch gets around and more people take advantage. The end result for someone with this inability to say no is to spend so much time in dealing with requests from others that their own output begins to suffer.

But how do you say no to someone who is asking you for help? This may be a colleague you have known for a considerable time and have built up a good working relationship with. To turn down his or her request may well make you feel like you are letting them down and this can lead to feelings of guilt. But if the request they are making is unreasonable, then you have every right to turn it down. If anyone has pangs of conscience about the outcome, it should be the other party for making an unfair demand upon you and not you for refusing to do it.

One of the things you should always bear in mind is the fact that you are being requested to do something, not given an order. A request comes in the form of a question, and a question always has more than one answer. So, by asking, the other person is offering you the chance to refuse, where in an order that option does not exist. Remember at all times that the person making the request is presenting you with the option to refuse.

The way in which you say no is also important. Obviously an abrupt 'go to hell' will do you no favours, but apologising and laying the 'I'd like to but...' on with a trowel can be seen as fawning and certainly not a demonstration of assertiveness. As with many things in life, the answer lies in finding the right balance. A refusal to an unreasonable request should be firm and direct, without a hint of nastiness. And once the word has left your mouth, all of those fears you had about being considered unreliable and letting the side down will materialise, won't they?

No, because the reality is somewhat different. Saying no actually shows that you are an assertive person and not a yes man. This is one of the skills your manager will be looking for when the next round of promotions comes up and so your refusals now could sow seeds that will bear fruit later. But there are other benefits that stem from this kind of assertiveness, and they are the ones that you will notice.

You will feel more confident as you have demonstrated that you can be assertive. You will feel relief that saying no wasn't as daunting as you had imagined and you will feel good in yourself for overcoming an obstacle. On top of all this, with your new-found ability to refuse those unreasonable requests, your own productivity should go up as well.

Keep those benefits in mind the next time someone makes an unreasonable request. Utilise your right to refuse and say yes to saying no.