The answer, apparently, is nothing as simple as true love, lots of money, or an exciting job. Instead, it can be neatly summarised in the following equation:

Happiness = P + (5xE) + (3xH)

Questions on which the equation is based

1. Are you outgoing, energetic, flexible and open to change? 2. Do you have a positive outlook, bounce back quickly from setbacks and feel that you are in control of your life? 3. Are your basic life needs met, in relation to personal health, finance, safety, freedom of choice and sense of community? 4. Can you call on the support of people close to you, immerse yourself in what you are doing, meet your expectations and engage in activities that give you a sense of purpose? See below to work out your score

Just to explain, P stands for Personal Characteristics, including outlook on life, adaptability and resilience.

E stands for Existence and relates to health, financial stability and friendships.

And H represents Higher Order needs, and covers self-esteem, expectations, ambitions and sense of humour.

Sound complicated? Actually, it isn't as difficult as it may seem.

Apparently the formula was worked out by psychologists after interviews with more than 1,000 people.

Life coach Pete Cohen, who co-wrote the study, admitted that the equation was not easy for most people to understand.

But he said it was based on a series of simple questions (see box).

Rating

Each person who completes the questions ends up with a rating out of 100. The higher the score, the more happy they are.

"Most people probably don't know what happiness is, they think happiness is perhaps having lots of money or a big car, or a big house.

"But people who have all these things are not necessarily happier than people who just enjoy their life."

Working out the answer

The questions should be answered on a scale of one to ten, where one is "not at all" and ten is "to a large extent" Add the scores for question one and two together to find your P value. The score for question 3 is the value for E, and question 4 for H

Mr Cohen said the British were expert at making themselves unhappy by focusing on negative things.

"We tend to be very obsessed with what is wrong, what is missing and what we have not got, rather than focusing on what we want and getting it.

"It would be nice to just enjoy your life, because life is a bit short."

The researchers found that different factors were important for the different sexes.

Pete Cohen came up with the equation

Four in ten men said sex made them happy, and three in ten said a victory by a favourite sports team.

For seven in ten women happiness was related to being with family, and one in four said losing weight.

Romance featured higher for men than women. So did a pay rise and a hobby they enjoyed.

Women were more likely to cite sunny weather.

Ingrid Collins, a consultant psychologist at the London Medical Centre, told BBC News Online: "I would be very surprised if people sat down and had to work out whether they were happy or not.

"We can all be happy in a heartbeat if we make the decision to be so."