As good as, if not better than, the demotivator posters at despair.com
I really hate the real posters these are based on. I cannot stand the shiny happy people that buy this crap and insist on putting them up in the hallways and meeting rooms at work. I wish I had the stones to buy one of the funny ones and replace the picture of those fucking skydivers.
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.