L5S1 disc space reduction

Hi,

I am facing lower back pain everyday in the morning when I wake up. The pain doesn't extend to my lower limbs and it wears off during the day while doing the mundane activities. 

My X-ray report says that I have a mild disc space reduction in L5S1.

I am a 27yrs old, 5"11, 85kgs, well built and not fat. I have a desk job but I don't need to sit in front of the laptop constantly frl ong hours. I have to do some running in between. I have a cotton mattress to sleep on which is comfortable.

Can someone please guide me on the causes and cure of the problem.