You just do.
Because the simple truth is that people are people just the same. There is no fancy or strategically planned list of rules to abide by because, like all people, moods and circumstances are subject to change every day. This isn't an article made to romanticize these diseases. The truth is holding them and whispering sweet nothings will do virtually that... nothing. While nice in theory, ideas like these that people suffering should be seen as lesser or "handled with care" help to feed into the stigma society has placed upon these illnesses. As if the issues they faced daily weren't restricting enough, now others are being taught new ways to further instill these ideas that they are not the same as anyone else.
This does not mean and is no way urging one to act with complete insensitivity toward these problems either. By all means if someone is struggling, be there to listen and guide and support them, but do everyone a favor and don't patronize them by appointing yourself as their own personal savior. No one is being helped when someone is being constantly "saved" from their problems and essentially taught that they are powerless to deal with them on their own.
Unlike a broken limb or a stomach virus, these illness are not the kind to be simply treated. Even with all the time in the world and an infinite amount of medicines, these problems may still prevail and may even still be inhibiting their everyday life. On the other hand, these problems should never be regarded as a joke or looked upon as lesser because of the average stander-by's inability to see them. Understand that one does not have "anxiety" because one is concerned about a test.
Even further, being upset about a team losing does not make you "depressed," nor does mistakenly thinking someone called your name make you "schizophrenic." Statements like these are also contributing to the diminishing of the severity of these illnesses and do nothing but make anyone who may suffer from one of these issues surrounding you feel extremely uncomfortable.
If someone confides in you that they are struggling, be a listening ear, and a support system. Do not patronize them with your newly acquired Facebook knowledge of their struggles and the way they should be "handled." Do not laugh off their cries for help; the idea that you cannot see their problems does not mean that they are not there, nor that they are not serious. When encountering someone with a mental disorder, do not act as if they are some fragile foreign being. The are people. Instead, stop and ask yourself who or what made you stop seeing them as such.