I would say, "Just because I see the glass as half empty, doesn't mean I'm unhappy."... "I realize at times I have a short fuse and I let stupid stuff get under my skin, however, I have come to accept my shortcomings and so should you."... "I know you meddling people mean well, but get the fuck outa my face!"
... I realize this may sound trite, but it really describes myself. I spent 15 yrs on meds... finally weaned myself off and realized I'm not really depressed.. just a half glass empty kinda person. Chirpy people annoy the shit outa me. lol