PAUL McKenna can change your life. He knows this for a fact - because he's already turned his own life around using the same techniques.

Best known for his stage and TV hypnotism shows, McKenna has far more strings to his bow than simply persuading burly lorry drivers that they are actually prima ballerinas.

And after a relentless quest for self-improvement, the 40-year-old from Enfield, north London, has earned himself millions and become friend and guru to the stars. Not bad for a former Capital Radio DJ.

''I frequently see people who are over-achievers, who still feel empty,'' he says. ''A few years ago, I was like that. I was achieving lots of things and not feeling good about it and wondering why. It was because I wasn't living my values and accepting myself, I was coming from a place of lack of self-worth.''

So he was inspired to change - and after ten years working on various techniques, he has produced his new book, Change Your Life In Seven Days. ''A lot of the stuff I've done on myself and other people,'' he says. ''I know it's worked because I felt significantly different quickly, and I got very different results in the world. It stopped feeling like such a struggle and my life became easier.''

The book is split into chapters dealing with things like health, wealth and relationships, and there's no doubt that the philosophy behind it has enriched McKenna's life. He may be laid-back in jeans, tidying up Christmas cards and restraining his enormous Great Dane, but his home is a Kensington mews house in west London and his car a black Ferrari.

''The real wealth, I have to say, is not just money. It really is about enjoying what you have. Over the years, I've met and worked with a number of people who are fabulously rich but not necessarily wealthy. And I don't have all the answers,'' he adds. ''I still have plenty of problems or challenges, because that is how you develop.

And McKenna is the first to admit that his love life hasn't been the most successful. His only engagement, to current manager Claire Staples, ended almost ten years ago, while an eight-month relationship with newsreader Penny Smith, ended in 2001.

Currently single, he jokes that he needs to hypnotise women into thinking he's Brad Pitt, and says he turned down a publishing deal to write a book on relationships because he hadn't enough experience.

''I said, 'I will if I can stay in one for any length of time'. I'm very good at moving on but don't seem to be good at staying. I'm probably a commitment phobe or something like that. Actually I did end up writing a book on how to move on at the end of a relationship.

''I'm rubbish, terrible, I think I'm a bad boyfriend. But I'd rather be on my own than stuck in an unhappy marriage. I know what it's like to feel unhappy, to feel self-dislike and to constantly feel like nothing is good enough. And I don't feel that now, or hardly ever. My goals have been very much career-oriented in the past. In the future I see greater opportunity for me to be in a relationship with somebody.

''It's not one of those things I think you can goal set - I will meet a woman by this stage, and I will marry her whether she likes it or not,'' he laughs. ''I don't think it works like that. ''I'd like eventually to get married and have some kids. If I don't meet somebody I want to marry it's not the end of the world."

Turning 40 was less of a shock to the system for McKenna than for most, he admits. If the milestone birthday makes many people take a long look at their life - and how it's different from what they'd hoped, he already evaluates his achievements on a six-monthly basis.

''I sit down and I look at where I was, where I am now and where I'm going and see if I want to make any changes. I think it's a good idea for people to do that. It's done a lot in the corporate world, but why don't individuals do that? Most people spend more time learning to work their food mixer or DVD player than their own brain.'' he says heatedly. ''Then they wonder when they don't achieve the things they want to, why they feel so overwhelmed by it. If you don't take responsibility for your life, nobody else is going to. Actually other people will, they'll tell you what to think and how to dress, and what to go and do.''

Change isn't hard, he stresses. ''You can change in seven seconds. If the doctor tells you, 'If you don't change this, you die', very often you'll change,'' he says with a wry smile. ''The idea that change is difficult and takes a long time is a myth.''

And he challenges anyone who reads the book and does the exercises - everything from visualisation to making life lists - to fail to notice a difference after seven days.

''If you follow these instructions it would be impossible not to. And that doesn't mean you have to be at rock bottom. In fact a lot of the people I work with are already in really good shape but they want to be even better.''

There's no doubting his passion for his work. He can talk almost indefinitely on his own career plans for the future - working on new psychological techniques, getting the self-improvement message across to more people and planning seminars and TV shows tackling everything from stuttering to infertility.

As a bit of light relief, he's created a show - a cross between hypnotism and candid camera, he says - with comedian Steve Coogan. And there are more live hypnotism shows on the cards.

''They're a lot of fun. I do enjoy it,'' he says. ''It's making fun of people a bit, but hopefully not in a horrible way. Like karaoke.''

* Change Your Life In Seven Days by Paul McKenna

(BantamPress, £7.99)