If you are a flight attendant, please watch where you swing your fat ass. As someone who sits on the aisle, I am sick of my upper arm being bruised by your protruding buttocks. Also, watch it when you are storming down the aisle with the cart. At least give a warning before you shatter a person's elbow.
And you, the asshole with the cellphone, no one cares that you are just getting on the plane or that you just landed. Wait until you are off the airplane and out in the terminal.
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.