References – AN 10.67: At Naḷakapāna (1st) 
“A question about physical pain. Sometimes it feels like I can deal with a certain level of pain, but every now and again there’s a level of pain that is too intense. Is there a technique for being okay with whatever level of pain?” Answered by Ajahn Amaro and Ajahn Pasanno. [Pain] // [Aversion] [Fear] [Goodwill] [Tranquility] [Buddha/Biography]
Sutta: SN 36.6: The Arrow.
Suttas: MN 53.5, AN 10.67, SN 35.243: Examples of the Buddha stretching his back.
Comment: In Viet Nam, native peasants needed less morphine than Americans paying for health care. [Health care]
Responses by Ajahn Amaro and Ajahn Karuṇadhammo. [Attitude] [Sickness]