The secret of happiness may be to not expect too much from life.

For if you start off with low expectations you could end up pleasantly surprised, according to a scientific study into human happiness.

British scientists found that day-to-day wellbeing does not reflect how well things are going, but whether things are going better than expected.

The ‘ebb and flow’ of mental happiness – the way our mood shifts moment-to-moment – is profoundly impacted by our expectations of life, they suggest.

Dr Robb Rutledge of University College London said his team were surprised to find just how important expectation is.

He said: ‘It is often said that you will be happier if your expectations are lower.

‘We find that there is some truth to this – lower expectations make it more likely that an outcome will exceed those expectations and have a positive impact on happiness.’

But his team of researchers, who tested their theory on 18,000 people, also discovered a converse force affects our mood.

While low expectations can make us happy if they are exceeded later, having high expectations to begin with make us happy earlier.

Dr Rutledge said: ‘Expectations also affect happiness even before we learn the outcome of a decision.

The results confirmed that people who started off with lower expectations were happier when they had better results.

The authors wrote: ‘Conscious emotional feelings, such as momentary happiness, are core to the ebb and flow of human mental experience.

‘Our computational model suggests momentary happiness is a state that reflects not how well things are going but instead whether things are going better than expected.

‘This includes positive and negative expectations, even in the absence of outcomes.’