COLON CLEANSE- is this really necessary? lol?

My sister keeps telling me to do one (she did it and was miserable & stuck on the toilet for 2 days LOL) but she may have a good point. I have eaten nothing but carbs & processed foods & alcohol for 15 yrs, and have recently made a drastic switch to only fruits, veggies, lentils, rice & fish. What do u think?