The number fear that people have is the fear of heights!  However you'll be very comforted  by watching this video.  Just concentrate of the gigantic cans and you won't even realize that you are watching a woman skywalking many stories above the ground.   In fact I think that is why this young lady is able to do what's she does.   Get lost in the cleavage and it won't matter.  

The video is of a Russian woman walking a thin beam that juts out from a Moscow high rise apartment building.   The woman has no harness, or safety net.  She is wearing a camera on her head filming the stunt.

I have a hard time concentrating on the stunt though.