Go on an unusual adventure.  Do something dreamy.  Create art.  Write a story.  Send a love letter.  Or send a letter or card to someone who you admire or care about.  Connect to your inner child and play.  Have fun.  Go swimming.  Or have a water gun/balloon fight (or build a snowman!).  Don't forget how fun life can be when you're not caught up being an adult all the time.