labour

a labour of Hercules a task requiring enormous strength or effort.

☞ In Greek mythology, Hercules was a man of superhuman strength and courage who performed twelve immense tasks or labours imposed on him as a penance for killing his children in a fit of madness. After his death he was ranked among the gods.

a labour of love a task done for the love of a person or for the work itself.

labour the point explain or discuss something at excessive or unnecessary length.