The basics of gratitude journaling is that you write down 3 or more things that you are grateful for each day. It can range from very small things (seeing a pretty flower, eating a satisfying meal, an extra hour of sleep on the weekend) or the grand (taking a vacation of lifetime, having a baby). I've found journaling useful in helping to shift almost any type of complaints I might have. It's not about being a "Pollyanna," but it is about realizing how much you probably have to be grateful for that you aren't aware of. So the next time you think, dang, "I have the clean the bathroom AGAIN"--catch yourself and also be thankful that you have indoor plumbing and how cool that actually is! Another trick I've learned is when you are paying a bill--say your health insurance bill or your electric bill--is to say "thank you" as your pay the bill (instead of griping in your head about the expense) for whatever service you are paying for. So as you pay your electric bill say--"I'm so happy to have air conditioning and light at night so I can watch my favorite movies and read my favorite books."
There are many gratitude journaling apps for iPhone and Android (which worked for me), but you can also use a plain 'ol paper journal.
Have you ever kept a gratitude journal? What was your experience?