Hercules and Antaeus
(Hercules was an enemy of Hera, and Hera is an Earth goddess, and so whenever Antaeus hit the ground, Hera was able to pour more power into him).
For one of his labors, Hercules had to fight a very strong man named Antaeus. But Antaeus had a special magic. Whenever he touched the ground, he could draw strength out of the ground and get stronger. Hercules kept throwing him down to the ground, but Antaeus kept getting stronger.
Finally Hercules figured out what to do. He held Antaeus up in the air while they wrestled, and so Antaeus got weaker until Hercules was able to kill him.
Learn by doing: hold a wrestling match
More about Hercules
Twelve Labors of Hercules (Step into Reading, Step 3), by Marc Cerasini. Very easy, for beginning readers.
The Story of Hercules (Dover Children's Thrift Classics), by Robert Blaisdell (1997). Very cheap.
Hercules, by Nancy Loewen (1999). Still easy reading, but more sophisticated, with a look at how the myth was passed on and what it meant to people, as well as the story itself.
D'aulaire's Book of Greek Myths, by Edgar and Ingri D'Aulaire. (Look under Heracles).
The Myths of Herakles in Ancient Greece, by Mark W. Padilla (1998). By a specialist, for adults.