تعریف و معنای "willing horse"

What is the origin of the idiom "willing horse" and when to use it?

The idiom "willing horse" stems from farmers relying on cooperative draft animals. Horses that worked willingly without issue proved better than stubborn ones. This led "willing horse" to signify cooperative over difficult succinctly. It now implies eagerness to assist without trouble, tracing to humanity's long equine relationship.