After reading so many books and online articles about back and leg pain, I sometimes forget there are folks that are coming across this for the first time. So, I will forgive the obviousness of the article title.
If you are having any of the serious symptoms (numbness/extreme pain) described in the article, please see a doctor immediately. If you have any bowel or bladder "issues," get to a hospital as soon as possible. It might be embarassing to admit you have those "issues" but it is a sign of cauda equina. You have very little time to get attention at that point as the long term effects can be just plain awful. I cannot stress this enough.
I have found it helpful to do the stretching exercises my physical therapist recommends. Do some core strengthening exercises, such as the ones highlighted at The Mayo Clinic. By keeping your core strong, your back won't put itself in a position to cause that sciatica pain you are having.