Hercules lost his temper and accidentally killed his family because he was cursed by Hera. After he regained sanity and he saw what he did, he couldn't live with himself.
He wanted to kill himself but his best friend Theseus stopped him and convinced him to make amends by doing 12 labors. He was given his labors by Eurystheus.
Hercules went to kill the beast Hydra in Lerna and was assisted by his nephew Iolaus. Hydra had an immortal head and a head that would replace it with 2 heads when it was chopped off.
For the fifth labor, Hercules had to drive away all the Stympalian birds because they were a plague to the people of Stymphalus. He received help from Athena.
Hercules needed to find the Golden Apples of Hesperides and deliver them to Eurystheus. Atlas was the father of Hesperides, so Hercules went to him for help. Atlas tricked him and Hercules was stuck holding the world, but then Hercules tricked Atlas and he was stuck holding the world again.
Hercules' twelfth and final labor was to bring Cerberus up from Hades. He was not allowed to use any weapons. It was challenging, but eventually he was able to make Cerberus submit to him. He brought it up to Earth to Eurystheus but he decided that he no longer wanted it and made Hercules carry it back down to the underworld.