Here's a stretch that seems like it was made to do in bed. It will target your lower back.
- Lie on your back in the middle of your bed. Bend both knees into the chest, and then cross them over to the left side of your body. You can even let your knees hang slightly over the edge of the bed for a deeper stretch.
- Extend your arms in T position, and gaze to the right.
- Stay like this for 30 seconds or more, feeling your spine lengthen and twist. You may even hear some cracks.
- Use your abs to lift your knees back to center, and repeat on the other side.