Which labor was the hardest for Hercules?

The hardest labor for Hercules is often considered to be the twelfth labor, which involved capturing Cerberus, the three-headed dog guarding the entrance to the Underworld. This task required Hercules to descend into Hades, confront the fearsome beast without weapons, and bring him to the surface. The challenge lay not only in the danger of facing Cerberus but also in the need to navigate the realm of the dead, showcasing Hercules' bravery and strength. Ultimately, this labor tested his resolve and highlighted the themes of life, death, and redemption in his mythological journey.