Chronic illness is known to be illness lasting 3 months or longer. For many, having something as simple as a common cold can take a toll on them, affecting their entire week. So you can only imagine how chronic illness lasting over 3 months, for many years or even their lifetime, can take such a toll on someone. It becomes much more than the physical pain and struggles, although trust me they're no walk in the park, but it becomes very mentally challenging too.
You're faced with the frustration of your body not healing itself. Then the frustration of doctors being unable to heal you. Then the frustration of the illness stealing your life from you. The list of frustrations and mental struggles goes on for miles, alongside with the fact that anxiety, depression e.t.c is often a symptom of chronic illness too.