TLDR: I messed up my lower back and could hardly move. Getting in or out of bed or a chair was excruciatingly painful and difficult. But with some experimentation I have found ways to work around the injury with minimal pain. If you have a lower back issue I hope this will help you:

Sitting down or getting up from a chair

Spread your legs and feet widely with your knees pointing outwards, in a sumo stance, then slowly try to rise or descend. This reduces the load and amount of movement required from your lower back. You can also brace your hands against your knees or thighs, and push, taking more weight off your back. 

Getting into or out of bed

1. Sit down on the bed using the technique above.
2. Slowly lean left or right until your upper body is leaning on the bed propped up by your elbow/forearm, with your legs still on the floor.
3. Now for the lift. The key is to bring your knees together and move both legs as a unit. Slowly bend your legs and lift them together onto the bed. As your upper body is propped up on one side, you are lifting your legs to the side, rather than forward. If your back problem is on one side, put the leg of your good side under the bad one to help take its weight.
4. Lock your legs and torso together, and roll your whole body as one unit onto your back, without twisting your waist.

Scooting around in bed

If lifting your butt off the bed to adjust position is painful, don't. Keep your butt on the bed to take weight off your back and concentrate on sliding it across instead. If your bed has a headboard, reach up and grab that for leverage.

Anti-spasmodics / muscle relaxants

The horrendous muscle spasms are your body's way of forcing you to not use the damaged bits. But since I have a low pain threshold I don't really need such an enthusiastic reminder. Muscle relaxants help reduce the muscle spasms from 'horrendous' to tolerable. A cheap over the counter option is Norgesic.

Good luck out there, it's a rough universe.