Like many seasoned meditators before him, Luang Por saw physical pain as an acid test of his ability to sustain clarity of mind in the most challenging of situations.
A meditation practice that could not withstand physical discomfort was seriously flawed; one that could transcend it, immensely powerful. Although it is true that the Buddha emphasized the value of good physical health and roundly criticized the excesses of the various deny-the-body-free-the-spirit religious groups of his time, it is also undeniable that generations of monastics have experienced significant progress in their practice through rising up to the challenge of illness.
A prolonged period of physical discomfort firmly handcuffs meditators to the nitty-gritty, and much is to be learned. Pain affords little room for self-deception. Dealing with illness and pain provides undeniable proof of how well meditators have developed their ability to protect the mind from anxiety, resentment, fear and depression when faced with the unpleasant.
If fear of death is still lurking in the mind, it is exposed.
This reflection by Ajahn Jayasaro is from the book, Stillness Flowing, (pdf) p. 117.