Herculean effort:
Hera was jealous of Zeus's son Hercules. She on numerous occasions tried to have him killed. Such as sending a serpent to his cradle, which he killed. But he persevered. Eventually he even married and had children. Hera caused that Hercules become mad from a poison and enter a rage, slaughtering his wife and children. He became so inconsolable afterward that he actually went to consult the Oracle of Delphi, which was unusual as Hercules tried to distance himself from the gods. It told him to go serve a king for twelve years to regain his honor. Hera told the kind what tasks to tell Hercules. There were twelve tasks, each very difficult. From slaying the Nemean lion to slaying the hydra to bring back the golden horned stag alive to capture a wild boar that was dangerous to cleaning out the Augean stables which hadn't been cleaned in years in a single day, then destroy the man eating Stymphalian birds, capture the Createan savage bull, then capture the four man eating mares of Thrace, obtain the girdle of the Amazon queen Hippolyta, capture the cattle of the monster Geryon, get the golden apples of Hesperides, which he tricked Atlas into getting for him, and taking the earth back again so he could get a better grip, and get Cerebrus the three headed dog who guarded the underworld to the surface without using weapons. He finally got to live a happy life, with a wife and kids again, almost was killed but became a God on the funeral pyre. Hercules lived an extraordinary life.
The term Herculean Effort refers to a task that's scope and difficulty would make it near impossible for a mere mortal to accomplish. Hercules had twelve such tasks he had to perform in order to be forgiven of the crime of killing his wife in a rage, even though he was not in his right mind due to a poison. The dictionary says: ."her·cu·le·an ef·fort :an task of great intensity or difficulty" in the modern usage, it refers to when one makes such an effort that it is very impressive for example, staying up all night to finish the project your team was to make by yourself; Or cleaning a mansion on your own in a day;Or fighting 20 men by yourself. If one can actually accomplish a Herculean task, it should grant one much prestige and honor.