using glycerin i spent maybe 1/2 an hour in the can. Not that but, just get a handheld videogame or some books
The preparation is the worst part of a colonoscopy, but it is just a total clean-out involving going to the toilet when needed each time as you drink the prescribed solution. You should not "be stuck on the loo", but you should not go too far away either. From my experience, you will not remember a thing about the actual colonoscopy. My doctor joked afterwards, "Are you ready to do it?", but quickly added that it was all over, and I had no rememberance of the procedure.
You generally start it the day before the procedure, and it will be a long evening. You may have to go an couple times, but not like you will during the day.