Like the man says, an exercise you can do first thing to get the spinal fluid moving.
Quite a long video, this workout includes many of the stretches and exercises recommended by the McTimoney Chiropractic Association.
This is a really important muscle in the lower back. You have one on each side which connects the pelvic crest to the lower spine and ribs. If it's over-tight, it can cause lower back pain and restrict movement - particularly forward and side bending. Here's how to stretch it.
Here's an exercise than can help with sciatic nerve pain. The aim is to try and get the sciatic nerve moving freely to-and-fro like a piece of dental floss.
Gentle exercises from Sarah Key if your back is in crisis.