Change a habit by adopting another one
I once observed a person just holding a cigarette and not smoking it. I Asked him about it and he explained that he used to be a smoker and wanted to quit and he came up with this habit to cut down on the habit of smoking. Basically he came up with a new habit to stop an existing one. He was apparently successful when I came to know he ultimately stopped smoking.
Want to cut down on coffee drinking, replace a cup with green tea. you still get the caffeine.