For a long time, I had two big phobias that severely hindered my day to day life. One was a phobia of tall ceilings, or altocelarophobia. It might sound strange and random, but I definitely had it. Upon entering a building, my eyes would scale up the walls, seeing how high they went. If it went up one or two stories, no problem. I was used to that pretty much everywhere I went. But if it kept going and my anxiety started to rise, I would immediately look down at the floor and pretend that the ceiling height was normal - until my anxiety passed, or I was able to exit the area.
The sky didn't count, in case you were wondering about that. There is no ceiling to the sky. Not that we know of at this point, anyway.