Golden Capsule on level one
On the first level, where you have to get to the Dragonball before Raditz and Nappa, defeat all the Saibamen that pop up until a red one appears. Fight that one and win. You should get a new capsule for Hercule. Equip the capsule, and whenever Hercule's health drops below one sixth he will now receive a boost of energy. This may require a few attempts.