Saitama from One Punch Man is incredibly strong because his body is far beyond human limits, giving him overwhelming strength, speed, durability, and reflexes. He gained this strength through intense physical training—100 push- ups, sit-ups, and squats, plus a 10 km run daily for over a year—pushing himself to the brink of death and supposedly "breaking his limiter," a theoretical limit on a being's power. This limitless physical ability allows him to defeat any opponent effortlessly with a single punch, making him the most powerful character in the series. The true origins of his power remain mysterious, but it is implied that his intense willpower and training removed any natural limits on his strength.