You can either make a list of what you have, or you can make a list of what you do not have. The first list will bring you peace and happiness, while the second list will bring you only sadness. Being sad and focusing on what we do not have does not change the circumstances.
Source: 6 Empowering Lessons Death Taught Me About Life @ tiny buddha: simple wisdom for complex lives
image: Jealousy by Luke Saagi under Creative Commons license