Give! Give a compliment, give your time, donate to a cause, or just go take a walk and smile and say hello to people give your happiness and feel happier
Dress the part! Ditch the black and put on some yellow, safety orange, neon blue, or screw it all of the above for a good laugh.
Go to the pet store and play with puppies!
If you know someone with a baby go visit and hold a baby, kids can brighten any day play with them they say the silliest things!