A job, task, or activity that requires a huge amount of effort, energy, or physical strength. Sometimes used ironically or hyperbolically. But getting enough votes to pass the controversial legislation may prove to be a Herculean effort. Sometimes it feels like finding a good burger that isn't the price of a sirloin steak is a Herculean effort. It will be a Herculean effort for them to dethrone the former champions in this year's Super Bowl, but they certainly have a shot.
See also: effort