I'm still pretty fit, but just have to remember that the Morphine is hiding a lot of damage. The last scan looked a lot better, so we decided not to operate again, and instead try injections and a course of physio. I still work out, but no dead lift or squats etc, as not worth the risk just to gain a few inches on the thighs.
Running isn't good for your back, nor early morning exercise, but walking will help to ease any stiffness. It might be you've trapped a nerve as the disc was disturbed / damaged.