The secret to happiness is keeping busy, research has found.

Keeping the mind occupied with tasks - no matter how meaningless - staves off negative emotions, the study found.

However, the bad news is that humans seem hard-wired to be lazy in order to save energy, according to Professor Christopher Hsee, a behavioural scientist at Chicago University.

In a study 98 students were asked to complete two survey. After they had completed the first they were made to wait 15 minutes to receive the next one.

They were given a choice of either handing in the first survey nearby or at a more distant location they had to walk to. Whichever option they chose, they received a chocolate bar.

Two-thirds (68 per cent) chose the lazy option.

Those who had taken the walk reported feeling happier than those who had stayed put.

Prof Hsee concluded keeping busy helped keep people happy.

He said the findings, reported in the journal Psychological Science, had policy implications.

"Governments may increase the happiness of idle citizens by having them build bridges that are actually useless", he proposed.

At the individidual level, he advised: "Get up and do something. Anything. Even if there really is no point to what you are doing, you will feel better for it."

He added: "Incidentally, thinking deeply or engaging in self-reflection counts as keeping busy, too.

"You do not need to be running around, – you just need to be engaged, either physically or mentally."

The academic revealed he had tested the principle by getting a research assistant to carry out pointless tasks.

"I know this is not particularly ethical, but he is happy," he said.