Our mothers always told us we should be thankful for what we have. Now there’s evidence that doing just that will make us feel happy and even improve our health. Robert Emmons, a professor of psychology at the University of California underook the first major study on gratitude.

In his book Thanks! he says it’s a crucial element of happiness. Emmons says it’s about wanting what we have, and he advises that we begin by acknowledging that life is good, and that the source of life’s goodness is outside ourselves – it can be a spouse, a child, a parent or God.

And he says gratitude should not be a reaction – it should be a state of mind.