I ALways knew yes, but having a horse made me reconsider this .. I think they are not like dogs that can SMELL your emotions due to a fine nose, I am very calm during riding but I have a horse that is scared almost by everything and very tensed. So I have this opinion that maybe they can’t really sense it, but sure they sense your tense position, however I don’t think they really care..
Oh yes definitely especially if you are very tense and you don't really want that. Since they can sense it they will most likely copy the way you feel and they will be jumpy, fearful, may not listen to you, will refuse jumps, ect.
Yes, Try breathing exercise before going to the barn, and tell yourself the good stuff about going to the barn and the good outcome it will be if you do go. Gotta keep positive and know you can do anything you put your mind to.