One is often told eating five portions of fruit and vegetables daily is “good” for you, but then winning a nice prize is also “good” and you would feel it immediately.

They are not the same thing of course, but it is worth quantifying what “good” means in dietary and lifestyle terms if one wishes to know whether it is worth following any specific advice which affects what you eat and do. And one interesting way is to express things in terms of lifespan changes.