It is always a good idea after a certain age that you get colonoscopy done. I have colon cancer in my family so my doctor started having me get colonoscopys every 5 years since I was 35. It will depend on what your doctor feels you should. If there is something wrong you will usually have symptoms like diarrhea, constipation, pain, excess gas and/or blood. If you are having problems you should talk to your doctor about it. If you have no symptoms and are just worrying relax because stress can cause problems. Worrying about things that might happen is a waste of time.