Sprinting to catch a bus, successfully, but then realising when you get on the bus that you haven't enough cash on you for a ticket and have to walk after all. For added points, do this when the air is cold enough to make running particularly unpleasant.

Still, I got there in the end, and a cup of hot coffee and one of Caffe Nero's extremely gooey and delicious gluten-free chocolate brownies made an excellent restorative.