a good deed is never lost

proverb An especially good, kind, or generous act is never done in vain. I know you're not crazy about Bill, but try to be nice to him anyway—if nothing else, a good deed is never lost. Who knows, you guys could end up becoming friends! A: "That cute girl still doesn't seem to have any interest in me, even after I helped her get her car started." B: "Well, a good deed is never lost. Maybe she'll help you out one day!" A: "I went through all that trouble to find her missing dog, and all she gave me was a homemade cookie!" B: " Ah well, a good deed is never lost."