For me, a "blue day" is usually good.
Today is such a day, a day when the air is right around the temperature of my blood. It's a day when the sky is so clean and bright that when you rub your thumb against it, it squeaks. It's a day when each individual leaf and blade of grass stands out in dramatic relief, as though the joy of life flowing through every living thing causes it to fluoresce in broad sunlight. The buildings look cleaner than they are, their edges sharp against the sky. The birds are gossiping. The cicadas are singing. A breeze is blowing. What am I doing indoors? I'm going out for a walk. See you later!
UPDATE: It was a wonderful walk. The sky is still squeaky-clean. I saw some cicadas on the wing, lumbering along like creatures almost too heavily built to fly. Most of the people on foot were younger, fitter, and much nicer to look at than I. At the farthest reach of my walk, I cooled off with a Dairy Queen treat (an old-fashioned ice cream soda, raspberry flavor--and though few know of it, the best thing DQ makes). On the way home I picked up four tall cans of Arizona tea for 50 cents each, thanks to a Walgreen's in-store coupon. And now I am nestled in the bosom of my cats, drinking an Arnold Palmer Lite Half & Half (half lemonade, half iced tea) and eying a sunny spot on the couch, where I might still get in a good hour of reading. It's one of those days when being alive feels good!