Before becoming Prime Minister David Cameron said a key goal of government should be to make the people of Britain happier. Traditionally the nation’s success was judged by its GDP or wealth, but Mr Cameron thinks that only shows part of the picture. So in 2010 he launched the National Wellbeing Programme; a series of measurements to monitor how well we are doing as individuals, as communities and as a nation.

The latest results suggest we are an increasingly upbeat Britain, with 73% of people giving themselves high happiness ratings. The government plans to use this information to help guide future policies, with the aim of increasing our levels of well-being even more.

But will becoming a happier population transform us into a more successful one? Tonight’s Jonathan Maitland takes a look at the science of happiness and discovers that improved wellbeing really can make a difference. Amongst other things, research has found that being happier helps you live longer and boosts productivity.

Nic Marks runs a company that helps businesses boost the wellbeing of their staff – and he says that happy employees help improve profits too.

We’ve done an estimate that for the average UK company which is 250 people, that having happy employees can save you half a million pounds a year.” Nic Marks

Some of Nic Marks' happy employees Credit: ITV / Tonight

So what are the factors that most influence our happiness? People often believe that money plays a big part -and that is true, but only to a limited extent. Studies have shown that the happiest salary is £45,000 per year. After that happiness doesn’t increase with every additional penny earned.

Tom Mitchell certainly doesn’t believe money is the answer. He gave up his career as a banker along with his banker’s salary to start a new life as a gardener. His buoyant bank balance ultimately didn’t bring him pleasure.

Money didn't buy happiness for Tom Credit: ITV / Tonight

I certainly found that all that having more money did is raise the game or raise the bar. So one compares oneself with peers and in banking there’s always someone with more money and once you’ve bought your first house there’s always someone with a better house, so you’ve got to move up that ladder and so on, so there’s never a point where you reach satisfaction.” Tom Mitchell

Whilst money can’t always buy happiness, one thing that does have a huge impact is the companionship of friends and family. ‘Cocktails in Care Homes’ is a London based charity scheme that holds monthly evening parties for elderly care home residents.

Smiles at a care home cocktail party Credit: ITV / Tonight

The residents sort of get excited and look forward to the parties, maybe weeks in advance. I think these cocktail parties offer friendship to older people that otherwise would never get that sort of intimacy” Clea House, Cocktails in Care Homes scheme manager

But the residents aren’t the only ones seeing the benefit – the volunteers also get a boost to their wellbeing, as research shows that doing good for others makes you happier as well.

So do we all have the power to make ourselves happier? Matthieu Riccard is a Buddhist monk, who is often referred to as the ‘World’s happiest man’. He believes that we’re all capable of training our minds into a more positive way of thinking.

'World's Happiest Man' Matthieu Riccard Credit: ITV / Tonight

Clearly we have different dispositions for happiness. That’s our baseline, that’s our starting point. But what we should know is wherever we start from there is a huge potential for transformation. That is what we vastly under estimate - the power of transformation of mind." Matthieu Riccard

Tonight wanted to see whether science’s discoveries on happiness can be used to boost our own levels of wellbeing. We teamed up with Action For Happiness, a campaign group aiming to improve society’s levels of wellbeing, and ran a group of volunteers through a series of social experiments. Tune in at 7.30pm tonight on ITV to find out whether we succeeded in making the group any happier.

The 7-day Happiness Challenge

Would you like to give your own happiness a boost? Here are four simple science-backed actions from the experts at Action for Happiness:

Three Good Things: At the end of each day, write down three good things that happened that day, including why those things were good

Kindness Day: On one day this week, do as many extra acts of kindness for others as possible (try to do at least 5)

Calm Your Mind: Follow the free Headspace "Take 10" program of mindful mediation for ten minutes each day at www.headspace.com

Move Your Body: Do something physically active (and enjoyable!) for at least 10 minutes each day

For more information about these actions - as seen on Is Britain Happy? - you can download the 7-day Happiness Challenge pack by clicking here.

Interactive Map

Click here to see an interactive map produced by the Office of National Statistics showing levels of wellbeing in your area.

Watch Tonight: Is Britain Happy? on ITV at 7.30pm.