You're a bit bored.
That's actually good news, though. Even the busiest people get a bit bored once in a while, and you've got two choices -- you can shake it off, find a way to refocus, and challenge yourself to do something awesome with the rest of the day OR you can give in to the boredom. Don't feel guilty if you pick the second option. You don't always have to fight boredom; sometimes you can wallow in it and give your mind a break. (You have total permission to take a mental vacation if you need one... everybody deserves time off from thinking once in a while.)