First, I'll echo Alec's comment. If you've been diagnosed with spinal stenosis, you should seek the advice of a qualified therapist. Additionally, you may wish to get another opinion and an MRI as x-rays are not the best indicator of spinal stenosis:
The X-rays can show the doctor various signs associated with spinal
stenosis, including loss of the normal intervertebral disc height, the
presence of bone spurs (osteophytes), and spinal instability (abnormal
motion between the vertebrae). The ultimate diagnosis of lumbar spinal
stenosis is made by an MRI scan (magnetic resonance imagining scan)
or CT scan (CAT scan or computerized axial tomography). These are more
advanced tests that are used to visualize the nerves in the lower back
and detect if they are being compressed from lumbar spinal stenosis.
However, having said that, and, as someone who has had prior experience with your condition, I can offer you some advice. I would caution you to not be overly aggressive in your recovery. As I commented in your previous question, spinal stenosis is a generic term for the narrowing of the spinal canal. It typically presents as a herniated, or, bulging disc. The disc protrudes into the spinal canal thus causing nerve root compression. The resulting symptoms can be debilitating.
In my experience, running would typically be contraindicated in your present condition because the force exerted on your spine would further add to any existing spinal compression. I would suggest you seek less aggressive exercises like swimming, or walking. Additionally, if you haven't already started a therapeutic stretching program, that's something you should consider under the guidance of a physical therapist.