So after advising people against keeping journals, Masello does a sort of about-face. In his second rule, he says that if you have the urgent desire to write, you should skip the "stream-of-consciousness twaddle" that shows up in journals, and instead, write a letter to a friend.
I think this is good advice, for all the reasons that Masello gives. He notes that the point of writing is to communicate, and that if you write a letter to a friend then you are, in effect, publishing a piece of writing for an audience of one. He also says that writing a letter will help you figure out what's on your mind, and that what's on your mind may be something you could turn into an article or a work of fiction for greater distribution.
I actually take Masello's advice further, but not necessarily in a way he would intend. (Then again, I doubt he'd object.) Sometimes, when I write a story, I aim it at a particular friend. This doesn't mean that I actually send a copy of it to that person, or ask that person for feedback; but sometimes, as I write, I keep in mind that my goal is to entertain this one individual, and if I manage to do that, then I feel I've succeeded.
By the way, Masello advises one to write an actual paper letter, and not just send an e-mail. I understand his perspective; there's always been something special about receiving a personal letter, just for you. Even with the explosion of electronic communication we've seen over the past decade, putting words down on paper often feels more permanent to many people. If you decide to write a letter to a friend in order to jump-start your batteries, I'd strongly suggest trying it longhand on paper and seeing what happens.