Often the sufferer would ask the above question.
Some percent of this is genetic (wearing out of cushions or discs) but a lot also depends on the person surrounding the spine. Therefore issues like weight gain, job profile (worst in sitting professionals), weak supporting structures around the spine (mainly stomach and back muscle strength) adversely affects the wearing off phenomenon.
A important thing to remember is that wearing off of the discs or spondylosis is arepetitive injury which keeps happening due to day to day activities of living. It is never a single event. It builds over a period of time. Most people would remember the period when they had this severe pain in back, but actually it had knowingly/unknowingly built up over a period of time due to lack of maintenance of the back and abnormal daily habits of sitting, lifting weights, relaxing etc.
Advanced stages of spondylosis build the stage for a nerve pinch in the spine (the nerve called spinal cord). The space available for the nerve in the spine is at the receiving end of advanced stages. There is a risk of developing a slipped disc or trapped nerves in the spine (called spinal canal stenosis in medical terms). This happens both in the neck and the lower back commonly. A spine surgery to relieve the trapped nerves (and hence the extremity pain associated with it) is extremely beneficial in properly selected cases. Check the related post “Results of spine surgery“. Not all people with spondylosis need a surgery.
Nobody can beat ageing or spondylosis. Although what is in our hands is to develop good habits. Hence developing a healthy lifestyle with controlled weight and good exercises helps develop healthy neck and back. Also read 5 tips to prevent back pain