I would like to offer my experience in dealing with this difficult challenge.
At first, I really was uncomfortable in discussing or even revealing my illness. I was still trying to accept it for what it was, and come to terms with the reality that I couldn't beat it on my own. For me, as for many others with a mental illness, medication was necessary.
I learned some key lessons between the time my first symptoms appeared in 2002-03 and my return to balance and health in mid 2005. For me, it came down to two simple questions:

1) How do you think and feel about your illness specifically and mental illness in general?

2) How does the person you want to discuss it with feel and think about these topics?

The former is the really important one, because if you feel guilt, confusion, anger, stigma, etc. about your illness and you are misinformed, how can you possibly speak about it? That's where I was for a while, so naturally I couldn't / wouldn't talk openly about it.
The hardest part for me to learn was that even after I went through the long and difficult path to that healthy place of acceptance, knowledge, awareness and perspective, it still wasn't enough for everyone. Even though I saw my illness as in fact physical (a problem located in my brain), and I understood that the term 'mental illness' does not equate with 'emotional illness', it was clear that others may take ages to come to this realization, while some never will.
Those people may be your colleagues, your friends, or one of your family members. It is difficult, but it is beyond your control. In my case there is one or two in each of those groups.
I was encouraged to find that once I reached a solid foundation in my own thinking, most of the people that I spoke to about it came to a place of understanding. Most people know instinctively that social attitudes towards mental illness are archaic and narrow, and if not they are open to understanding this. They want to feel included in your experience, and understanding what you are dealing with is part of that.
So for the most part, it came down to me. Once I reached a healthy level of acceptance and spoke comfortably, knowledgeably and plainly about my illness, I saw that most of my listeners were eager and positive. The others, well, I just learned to accept their limitations and I live with the hope that as long as I remain consistent in my message, they may come around.
That has been my experience, and I hope it can help you in yours.

Be well,
Jason Finucan