I tend to wrench my back every few months. I work out daily......not sure how to prevent?

Degeneration. Unfortunately we all get older every day and our bodies change over time - in the spine, the discs will wear out and can start to bulge and you can start to get bone spurs. This degeneration/arthritis causes the episodic pain that you and many other people experience. Basic health measures are your best bet - exercise, weight loss, good diet, quit smoking, increased activity.