slang To be in a favorable or enjoyable situation. I think I'm on to a good thing with my new job because I can work from home as much as I want.Your new boyfriend seems really sweet—I think you two are onto a good thing.
to be in a pleasant or successful situation 'My wife does all the housework and cooking.' 'You're on to a good thing there!' (often + with ) He's on to a good thing with this chauffeur service he runs.