My favorite is a silver butterfly necklace. One side is inlaid and one side is engraved with, "Just when the caterpillar thought the world was over, she became a butterfly".
I have a belov'ed coat that I can't fit into anymore. Soon as I started this diet, I installed a coat hanger next to my work computer and hung it up as a reminder of why I'm doing this.
"No one ever said it was gonna be easy"...
I used to say this to myself if I was really struggling to finish a project, etc. I apply it now to weight loss.