The formula in the subject is true, but it turns out that we are not really that good at figuring out odds and value. This causes issues with your happiness. Comparison and contrasting things further impacts this decision making.
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.