A Zimbabwean man has talked his way into what could be a new Guinness world record with a speech lasting 36 hours. Mungoshi was only allowed "natural pauses" of not more than 30 seconds and was permitted to take 15-minute breaks every eight hours to eat and go to the toilet.
36 hours is nothing.
Ask anyone who has been unfortunate enough to be in the company of someone who has taken a lot of speed. Those guys will talk your ears off for days, taking breaks only to do another line and beep their dealer for more. The speeches are not so formal. Mostly they consist of very intricate conspiracy theories, complaints about the cost of speed and "What was that noise? Who's there? Hide the stuff, man."
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.