I herniated a lower disk this past March. Found out then that it's a degenerative disk from a previous injury some 15 years ago. Since having herniated it this last time I've had to be careful how I lift things and has slowed me down considerably. I used to be more active but it just doesn't take the use and abuse that it used to. There are several exercises that I do to help me with it. My favorite one I call the half pushup. Keeping my hip and legs flat on the floor I do a push up of my upper body. Even then I have to be careful how I do it because if I try to push up all the way when the disk is hurting, it jolts me with a sharp pain. If done carefully it does cause the "fluid" in the disk to even out again (insted of flowing to the back of the disk from bending over and/or lifting things) and that, hopefull will keep the disk in well enough shape to continue on with normal daily activities.
As to exercise, I've avoided sit ups, afraid that will put too much stress on my lower back and have been using ab machines at the gym. Though now I've moved and this gym doesn't have those machines so I have to figure something else out.
You might find the exercises discussed in this article (and demonstrated in the accompanying video) to be worth a try.
