In India they say you are as young as how flexible your spine is. Keeping your spine flexible should be one of your major goals. It could mean simply swinging side to side or rolling your spine forward and back a few times a day.
However, if you already have a pre-existing condition, like an inflamed disk, please consult your doctor to see which stretches you need to avoid.
This video gives you an overview of the way our spine is meant move. And a great start for a gentle practice.