For example, if you are painting your house (a form of manual labor), you can see right away where to brush next. But when you get a hundred emails a day (a form of knowledge work), most of which do a pretty poor job of getting to the point, the next actions don’t usually come to you predefined. You have to figure out what to do with each email, then figure out how to fit that in with all the rest of your work that you have had (or have yet) to define.
