I'm happy to be open about mental health issues. I have had enough negative experiences with, and read broadly enough about the theory behind psychotherapy to have come to my own conclusion that it makes about as sense as most dogmatic religions (very little).
That's pretty stereotypical. The happiest people on the outside can hide some pretty dark clouds on the inside; especially in a work environment where outward appearances are important. In fact, I would suggest that the majority that are depressed don't show any outwards signs to working colleagues.
It's my way of compensating for every relentless, hammering, baseless urge to die that I've survived alone over the years. It took a long time for me to get that people don't typically understand that it's more like hiding that you have cancer than not being able to cheer up. You can hide the symptoms of both, you don't ask for either of them, and they might both kill you, but somehow you're responsible when you get depression but not cancer.