Do something fun today. Preferably, do something fun that's active. Go ahead - be wild! How about going to a water park, or playing golf? (Have you ever?) What about a rousing game of bowling? Is there a playground near you? Go swing on a swing, or ride the merry-go-round.
If you feel self-conscious, just say to yourself (or to anyone who asks) "I'm having a second childhood." Besides, there's nothing wrong or illegal in having fun and enjoying yourself. Go for it!
Enjoy this day, this moment as a gift that God gave you. Remember the old saying, "All work and no play..."