These are my favorite stretches for the hips and back! They should be done on a mat on the floor, or in bed (on a reasonably firm mattress). I hold each stretch for 30 seconds. One set takes about 6 minutes. I repeat the series, and add a bonus stretch at the end. If you only have 6 minutes to spare, just do the first set.
[Disclaimer: Not all movements are appropriate for all bodies and there are inherent risks in any type of physical activity - yes, even stretching! Pay attention to how your body feels before, during, and after the movements and do not attempt any stretches that your doctor has contraindicated.]