As someone here has already said, it largely depends on what exactly is making me glum.

1.) PMS: Extract of Chastetree berry. 2.) Grey day: Think about next sunny day (when it's not *too* cold) when I can take a drive in my convertible. 3.) Bad day at work: "Red Dwarf" in large quantities with my sweety. 4.) Interpersonal political BS/flames/injustices/double standards/"holier than thou" crap: Get the hell away from it, and spend some time amongst the sane. 5.) Death of loved one/acquaintance: Time with other someones to reconnect, and share the mourning.

If all else fails, the turning of the earth always helps.