That's so shitty. I caught the flu on my birthday once, but that's my own fault for making out with my ex. Last year I had a broken foot on my birthday, and by the time it was healed enough to go anywhere, no one could have taken me seriously for still wanting to do something "for my birthday". This year was great, though. Got sushi with my bestie, went to a pub quiz, and talked for 12 hours on the phone with my brother. I totally support your blimp plan -- if you don't have a very good reason for not doing it after all, you're just gonna resent that for the whole year until your next birthday.
Have I missed anything?