Years ago I read about an author who wallpapered her entire bathroom with rejection slips from editors and agents. I don't remember now what this activity was supposed to accomplish, according to that author, but I do remember thinking that I, personally, would not feel encouraged by facing a rejection-wallpapered bathroom every morning, especially before I've even had my coffee.
What WOULD encourage me is some clear, no-holds-barred explanations of why stories remain unpublished. This is the kind of encouragement I found in Jessica Page Morrell's book, Thanks, But This Isn't For Us: A (Sort of) Compassionate Guide to Why Your Writing Is Being Rejected. Morrell, a developmental editor and writing teacher, takes the reader through fourteen chapters that cover everything from the first line to "The End," pointing out potential manuscript weaknesses that even the most careful writer might not be aware of, plus a helpful glossary of publishing terms.
Morrell's approach is not delicate--in fact, "blunt" might be putting it mildly--but she gets her point across. Think of it as tough love for the writer's soul ("soul" being something she's not crazy about, by the way, as in "she felt his passion in the depths of her soul"--phrasing she calls "cringe-worthy." I told you, this is not a book for the thinnest of skins!)
Even if you haven't yet finished your story (or haven't even started it; I'm looking at you, NaNoWriMo participants), you'll still find useful information that might help you swerve around some potholes in the first place. So the next time your manuscript receives a rejection letter, instead of posting it on the wall next to your toothbrush holder, try reading through it with a copy of Thanks, But This Isn't For Us at your side. It just might be a more effective brain stimulant than your morning coffee!