Not a muscle — a plow. The oracle-bone 力 is the wooden digging tool a farmer leans his whole weight on: strength is what it takes to break the earth. Wherever 力 appears in a character, someone is working hard.
A piece of culture
The old man who moved mountains China's favorite story about strength is not about muscles. The "Foolish Old Man" (愚公) lived behind two mountains that blocked his way, so he began digging them away, bucket by bucket. A wise man laughed at him; the old man answered: "When I die, my sons continue; then their sons, and theirs — the mountains will not grow." Heaven, moved by his persistence, carried the mountains away. Two and a half millennia later, 愚公移山 is still what Chinese say when a task looks impossible: keep digging.
Use it in a real word
人力
rénlì · jan4 lik6
manpower — person + strength; every wall and canal in this course was built with it