Increasing your flexibility by performing a lower back stretch is a good idea to not only reduce the risk of injury but also make your every day life easier. As we age our muscles have a tendency to tighten up and the joints also become limited in their range of motion. This makes it harder to do the activities you used to love so preventing this before it starts is critical. A lower back stretch is just the thing to help.
One great lower back stretch to perform is done by sitting on your shins next to the floor, bum touching the toes. Then slowly lean forward with your upper body, stretching the arms out as far ahead of you as possible (elbows should be straight). Next take a deep breath in and then think of pressing your stomach as far into your thighs as you can. Hold this position for about thirty seconds.
Then, reverse the action so that rather than pressing your stomach into your thighs and making an arch in the body, round the body so you are hunched over. This will help to lengthen the spine and improve flexibility in the other direction.
An alterative way to do this exercise would be to simply grasp on to a pole or fixed object while in a standing position. Then pull backwards while arching your body the same way you did in the second portion of the exercise above. The more you lean your body weight outward the greater the pull you will feel. It will likely help to put your head down slightly so as to not strain your neck as well.
So when you are feeling a small amount of discomfort, or even if you just want to relax, try doing either of these exercises.