A pain-free body is the basic pre-requisite for a happy mind. However, when we are young, we take our health most casually & often for-granted. As a consequence, while we do remain fine in our youth, the ravages suffered by our body & the casualness by us over time towards our most loyal companion i.e. our body, starts reflecting upon us prominently sooner or later.
Slowly & gradually, pain sneaks upon us & starts snatching so much from us silently. We start initially by tolerating pain & then getting used to it. We start taking painkillers to relieve us mostly. They work well initially, but prolonged usage of pain killers comes with a baggage of side effects & damage to our critical organs like kidneys & liver to start with while spreading its tentacles over the entire body over time.
While we may ignore initially, things intensify as the painful conditions progress. Depending on our targeted organ like the knees, or spine, or neck or joints, etc., we start our visits to doctors & get tests, X-Rays, etc. done and then get entangled in a vicious cycle, which usually end up in surgery.

