When we observe other people in pain, we feel pain ourselves. This is because people are able to feel empathy: the capacity to understand what another person is feeling from within the other person's frame of reference, this is, the ability to share the feeling of others. Not only adults, but children and adolescents also, exhibit empathy. However, some people suffering from pathological conditions such as autism spectrum disorder, psychopathy and alexithymia show emotional blindness and have huge difficulties in exhibiting empathic behavior.

Why do empathic people feel the pain of others more?
Interestingly, the same brain areas that are active when we feel “our pain”, are active when we observe the social pain of others. Indeed, observing the pain of others increases activity in the insula and anterior cingulate cortex, the key social pain-related regions which are activate also when directly experiencing our own pain. Moreover, observing others’ pain activated the prefrontal cortex PFC and temporo-parietal junction as well —brain regions associated with mentalization (i.e., ability to understand the mental state of oneself and others). That is, ideally, in empathic people, both the mentalization and the social pain-related regions should be active. The higher the level in empathy, the higher level of activation in those areas.

So yes, your pain is my pain, but this is particularly true the more empathic we are and, from this point of view, empathic suffering is a real and true experience of suffering.