Andy Griffith, at the beginning of his comedy career, created one of the most hilarious bits of all time called "What It Was, Was Football." The single, a tale of a young southern man's first visit to a football game, sold a million copies. This always made me laugh out loud.
The Archive of American Television has a great series of interviews with Andy Griffith over at Google Video. The one I link to discusses his early days of doing standup comedy tellin' Shakespeare and his start on TV. It is a fascinating interview. It is so amazing that this material is available online.
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.