You can do the entire stretching exercise program in 20 minutes or less. Hold each stretch for 5 seconds and repeat a few times, up to 10 times.
Stand with your back to a wall. Press your heels, buttocks, shoulders and head against the wall. Move the feet forward, and bend your knees so your back slides a few inches down the wall. Tighten your abdominal muscles so you can flatten your lower back against the wall. Relax. Repeat.