MY appt with colon and rectal dr?

The dr had some scope thing with a light on it, couldn't really tell what it was but he said no fissures or tears and hemorrhoids weren't actn up, but he said I needed a colonoscopy to find out why I have been having the blood for 1 year and a half. He said my blood work was great and that I am not anemic (What would amemic have to do with it), Bloods coming from somewhere, anyway now I am nervous, because I thought it would be hemorroids or tear, but I guess it is more serious. Anyone had colonoscopies and how did it go for you?