I've had 2 major surgeries that I really remember. I had both of my ACL's reconstructed and then when I was young I had tubes put in my ears but I don't remember a whole lot about that..just a little.. For the 2 knee surgeries I was in my teens and I was absolutely terrified the first time. I had heard so many stories about things going wrong and people actually being awake when they thought they were asleep and so on and so forth (Total load of bull I'm sure, but I was pretty young..early teens..and I didn't know any better). I almost didn't have the surgery..the doctor had to give us a couple of days to think it over. I cried and cried and cried. In the end I had it done and everything went fine. Then two years later I blew out the other ACL and had to go back in! It was much less terrifying then because I knew things would go smoothly and I would make it out perfectly fine in the end.
My best advice is to try not to think about it for now. Think about other things. Keep yourself busy cleaning while listening to your favorite music, watching movies or surfing the horse forum ;)! Lol. Just relax and focus on what is ahead. You will make a great recovery and then it will all be behind you!
I had shoulder surgery in December and right before they put me to sleep my heart rate went up and all the machines started beeping lol. My best advice would be to think of something else and how much better you will feel when you wake up. Good luck and let me know how it went! 
