huán, not the more common hái).The characters literally combine to mean “return (from) old age, revert to childhood.” The structure is direct and paints a powerful, almost magical, picture of the aging process being reversed.
internal achievement. It's the result of one's own efforts in cultivation, discipline, and harmonizing with the natural order (the Dao). This reflects a cultural value placed on self-cultivation and inner balance over external quick fixes.This idiom is almost always used with a positive and admiring connotation. It's a powerful compliment.
preserving youth, whereas `返老还童` is about regaining it.