I've had two colonoscopies and they were painless. The day before a colonoscopy you generally live on a liquid diet for 24 hours(clear broth, gatorades, water, jello, but generally no red stuff). You don't usually eat or drink anything started at midnight the day before your surgery(not even water). When you go in, the nurse will instruct you to get into a gown, and then lay on the bed. Then the nurse will put an IV in your arm, which is painless, and then you will wait for your doctor. When he is ready they will wheel you into a room, and have you turn over on your side. The doctor will talk to you about
the procedure etc., and then shortly you will be waking up disoriented. Done.
I wish you the best of luck!