Whenever you suffer pain, have ready to hand the thought that pain is not a moral evil and does not harm your governing intelligence: pain can do no damage either to its rational or to its social nature. In most cases of pain you should be helped too by the saying of Epicurus: 'Pain is neither unendurable nor unending, as long as you remember its limits and do not exaggerate it in your imagination.' Remember too that many things we find disagreeable are the unrecognized analogues of pain - drowsiness, for example, oppressive heat, loss of appetite. So when you find yourself complaining of any of these, say to yourself, 'You are giving in to pain.'
Take care that you never treat the misanthropic as they treat mankind.
Mind over body. It is easier said than done, but humans have proved time and time again that pain is tolerable. Pain, cannot damage the rational or social nature of humans. There is no need to suffer pain twice. You are in pain; let it stop there. Do not add, "And it hurts so bad!! I am suffering!!" If you do, the additional pain is self-inflicted. When you complain, you give into pain.
The definition of misanthropic is "disliking humankind and avoiding human society." This is another way of Marcus saying, don't be like people who harm. In another passage, Marcus says the best revenge is to not be like your enemy (6:6).
(see also Citadel p. 58)