My sister writes down three things for which she is grateful everyday for a year.
I drew an angel card called "Family Harmony" that told me to think of three things for which I am grateful about each of my immediate family members. I immediately did so, since it is easy to find many reasons I like these people. The afternoon and evening were absolutely cheerful and precious.
Mental note: Use this trick during times when I am annoyed about some item not being put away.