It's an interesting question. It seems simple on the face of it but, I don't think it is. Comparatively speaking, I probably don't have a shitty life. My health isn't too bad. Thanks to inheritance, I am able to live independently and I could afford to pursue the education I wanted and, more or less, eventually land the job I wanted. The things I don't have- close friendships and relationships, I have chosen to neglect.
But, I'm (obviously) not happy. I'm tired of working- even though it's what I wanted to do. I'm tired of the pressures of having to financially and practically sustain this life. Really then- it comes down to a question: 'Is it shitty to be expected to work to sustain life or, is that a reasonable expectation to put on someone?' Am I 'mentally ill' because I resent having to comply with this world?
In a weird way, I'm not so sure either apply to me. My life isn't excessively shitty- although I have a lot of shitty childhood baggage. I'm not convinced I'm mentally ill either. Not debilitatingly so anyway. I'm just tired mostly.