By working in the emergency department of a hospital, I see people in pain on a daily basis. Some in a more serious condition than others, but in pain just the same. One of the first questions they ask you upon arrival is to rate your pain on a scale from 1 to 10, with one being little to no pain at all and 10 being the worst pain you've ever felt. I have witnessed a patient with an earache give their pain a 10, and I have seen a patient in cardiac arrest give theirs a three. That's the thing about pain; we all handle it differently.
We mainly base the severity of others' pain on what they tell us, seeing as we're not able to feel it ourselves. If someone tells you they're at a 10, you treat them as a 10. Of course there are the outward signs that help us form our conclusion as well. If a person is wincing, tears streaming down their face, gripping tightly to the area associated with the pain, it's safe to assume they are hurting.
But what about emotional pain? Is it possible for a person to have a smile spread from ear to ear, even though they're on the verge of breaking down? Can someone laugh the loudest at every joke even though sometimes they feel as though their life has become one? Could the brightest person you know actually be surrounded by darkness?
Physical pain is comparatively easy. Easy to see, easy to approach, easy to heal. While it's hard to ignore a broken arm, a broken heart can be easily hidden. So I challenge you to talk to people. As simple as that sounds, it's becoming less and less popular in today's culture to ask someone how they're doing and care about any answer other than "good."
So ask people if they're okay, let them know that you're there and keeping in mind that we all handle pain differently, treat them all like 10's.