Three words: Don't Push Back. (Four words: Don't Push Back. Ever.)
How do you teach them that, though? I'm assuming there's more to it that just explaining those words to them, but I'm wondering what the teaching looks like in practice, if they aren't actually dealing with pain when they're training. Is it like, they are taught and practice not pushing back and the goal is to make it enough of an automatic habit that it they do encounter pain, they already have the right habit of how to respond? Or there is occasionally some pain, it's just very mild, but it's enough that they can try out ways of responding and learn the correct response that works and cement it into the automatic part of their brain? Basically, if they don't encounter pain when they're training, how do you prevent the panic response when they do encounter pain, where they get surprised and respond in a way that makes it worse? Or have I misunderstood what's meant by not causing pain?