One of the best lessons from Tim Ferriss' The 4-Hour Workweek is how firing clients can make you happy. It fits into the 80/20 principle, or Pareto's Law. Think about it this way as Ferriss exemplifies in the book: "80% of the consequences flow from 20% of the causes. 80% of the results come from 20% of the effort and time. 80% of company profits come from 20% of products and customers." It can be......