Lower Back Stretch (and Glut. Muscles)

• Lying with your head and spine flat on the floor (or any firm surface) pull one knee toward the shoulder on the same side. 
• The opposite knee should be flat on the floor.
•  Hold for a count of 10-15 seconds.  Repeat on both sides 3-5 X's or until stretch is achieved. 

Modification: Pull the knee toward the opposite shoulder.

As with any exercise, if you have any health concerns always consult your doctor first. Some exercises  may not be suitable for your condition and may cause more harm than good.