The pain provides a chance to recognize suffering. The pain reminds us to free ourselves from suffering. The pain is a partner for a real practitioner, if we can listen carefully to it, we’ll understand the pain doesn’t arise from its own side. The pain contains dependent conditions in the moment of physical and mental birth and death, where the suffering lives.
The pain will help us to understand suffering, but the pain itself doesn’t have to be suffering. The pain is just a state of sensation, it will not become suffering until it is grasped by the differentiation of “like or dislike”.
The pain will cultivate the power of persistent effort to deal with any other afflictions. When the pain appears, we should neither resist against nor attach to it. It is not your enemy or barrier, it is not you or yours. You should keep looking at it but not get involved with it. You can loose your posture when you feel exhausted but don’t lose your awareness.
The pain is showing its emptiness in every moment of now, but we neglect and would rather to grasp its illusive solidness, which is disguised by the continuous physical and mental forms. They looks constant, but there’s no single birth or death, they are just dependent arising moments. And when we intend to develop them into slides of moments, we ignore that it is empty in every split second. That’s why it is said in Heart Sutra: …neither produced nor destroyed, neither increasing nor decreasing…
No pain no gain. And if there’s no "pain", there’s no "gain" : )