I damaged my L5-S1 when I was in my 20s.

Two things have helped me greatly.

1)

Lie down on the floor - not on a cold surface. At first you will need to do this with your knees elevated, but as you get the stretch working, you will be able to get them down on the floor.

The 'trick' is to get your spine as close to the floor as possible - at first you will find it is high off the floor so try gently to get it down there. As you get more strtech over time you will be able to keep it on the floor as you lower first one knee, then eventually both knees. This stretch can often give immediate relief (to the 'slipped disk' area pain) once you can do it.

2)

In the gym, there is a technique called 'fly's, where you hold a weight in each hand, your arms up at your shoulder level, and bring your hands towards and away from your chest.

What I discovered was extremely helpful to reduce back pain was 'half fly's - where you only do this one arm at a time. You lay on a bench, and at first you put your feet down on the floor, but as you build strength, you can balance yourself on the bench, feet up.

What you are strengthening are the 'spinal rotator' muscles, which are rather difficult to isolate, at least without having vertical weight on the spine, as most of the standard 'spinal rotator strengthener' excercises do. Most of the gym intructors had never heard of this technique - can't say I invented it! - but they all agreed that was great for assisting those with back problems, and could not aggravate the existing problems, cause the weight was off the area.

After a few months, I had worked up to 5Kg weights in each hand - hold one arm fully extended while doing the 'half-fly' with the other, also works things harder than holding it over your chest, If you get real strong, you can even swing BOTH hands to the left and right too!

When the 'spinal rotators' get very good tone, they hold the spine (the disks) tightly and I found far less pain from movement, even for years after.