On New Year's Day, depressed by yet another article on Britain's 'happiness crisis', I took a sheet of paper, ruled it in two, and in the left-hand column began listing all the things that were getting me down. This is what I wrote: 'My grey hairs... my impending tax bill... my failure to write a bestseller... the commute to King's Cross on the Hammersmith and City Line.' (The list was actually much longer than this, but you get the gist.) Then I turned to the right-hand column and began listing all the things that were a source of happiness in my life: 'My good health... my wife and children... my friends... playing tennis (when I win).'

To my surprise, this exercise immediately lifted my spirits, and before I knew it the items in the right-hand column outnumbered those in the left. Then I got to thinking some more. Were there other approaches I could adopt, other attitudes or ways of thinking about my life that would also be likely to increase my total sum of happiness? In search of an answer, I immersed myself in the works of Plato, Aristotle and other great philosophers. I also began reading as many self-help books as I could lay my hands on: books like the Dalai Lama's The Art of Happiness and Norman Vincent Peale's The Power of Positive Thinking - of which the cover of the UK paperback edition boasts 'over 15m copies sold'. But while these experts had many useful insights (the Dalai Lama suggested I cultivate a spirit of compassion, while Peale advised that happiness was a matter of being more optimistic), none of them spoke directly to my own experience.

Then I heard about Authentic Happiness by Martin Seligman, a professor of psychology at the University of Pennsylvania. In his book, Seligman describes how every New Year he takes a sheet of paper, just as I did, and draws up an inventory of his life. The difference is that instead of listing the things that are making him happy or unhappy, he writes down his key life 'domains' (love, profession, friends, play) and assigns them a rating on a scale of one to 10. Having performed this exercise every year for the past decade, Seligman says he can now see at a glance whether his happiness 'trajectory' is on the up or going down, and where there is room for improvement. 'I recommend this procedure to you,' he writes. 'It pins you down, leaves little room for self- deception, and tells you when to act.'

As a guru of the new positive psychology movement - dedicated to the optimisation of 'positive emotions' - Seligman argues that there are no short cuts to happiness. Enhancing joy, rapture and contentment depends on our cultivating optimistic personality traits and Aristotelian virtues such as wisdom, justice, love and humanity. 'Positive emotion alienated from the exercise of character leads to emptiness, to inauthenticity, to depression and, as we age, to the gnawing realisation that we are fidgeting until we die,' he warns.

The optimist proclaims that we live in the best of all possible worlds, and the pessimist fears this is true.
- James Branch Cabell

What the caterpillar calls the end of the world, the master calls a butterfly.
- Richard Bach

'I do not believe in free will. Schopenhauer's words:'Man can do what he wants, but he cannot will what he wills, 'accompany me in all situations throughout my life and reconcile me with the actions of others, even if they are rather painful to me. This awareness of the lack of free will keeps me from taking myself and my fellow men too seriously as acting and deciding individuals, and from losing my temper.'
- Einstein, 'My Credo'