Depression triggers. They're manyfold. Some examples for me:
--That well-meaning teasing about how forgetful or klutzy I am. Or admonitions from family and friends to just "slow down and think things through" more. As if I haven't been trying to do this all my life.
--Any reminder that normal people have a circle of dear, close friends who drop by all the time and hang out with them, or at least text/call them several times a day, while I get more calls from telemarketers than from friends and family (but also realizing that constantly being in touch with everyone is exhausting, because they make demands and expect you to help them with things, or to do things with them in the mornings on weekends and stuff, and realizing that I don't have many friends because I'm too lazy and selfish to allow relationships to change my schedule).
--girding my loins and doing something social (even if it's exhausting) and realizing that there is this inner circle of friends I'm not a part of within these activities and organizations, because other people will announce things to one another like "I just got a text from [name] and she says..." when I haven't even exchanged (or been asked to exchange) cell phone #s with anyone in the group.
--Being told, on those rare occasions when I pluck up the courage to initiate a conversation about my needs not being met in a relationship or situation, that the problem is actually all my fault because [insert something I do that's wrong], so I don't have a leg to stand on.
--Being told that I'm so smart and gifted that I would succeed at anything I wanted if I'd just try harder. This was both frustrating and terrifying when I was a kid/teen especially. Frustrating because it is absolutely impossible to prove to someone else that I am trying as hard as I can (or at least as hard as I know how to) and terrifying because trying one's hardest and failing means I'm really not all that smart or gifted after all, and my value and uniqueness as a human being lies in being unusually brilliant and talented.
--when I was a teen, buying a cute pair of white shoes or pants and having them become so stained/grubby the first time I wore them that I could never wear them again. Looking at all the other girls and their snowy white cute pants and shoes and realizing that there's something odd about me that simply attracts dirt and grime.
--Any kind of backhanded compliment, whether its intentional or not.
--Having a really good time at a social event, or having what felt like a really good, interesting conversation with someone and being told later that my perception of this was entirely skewed.
--Anything that reminds me of how sexist the world still is and of how few people (even other women) give a shit about that. Being told I'm over sensitive or imagining things when I complain about sexism, or that that's just how things are because "men and women are different."
--Other political and sociological types of things that remind me of how on the edge of social regression or how miserable the world is will also trigger depression, because I'll start to feel guilty about my concern with my own petty issues when life is genuinely screwed for some folks.
--Just looking at my messy, chaotic, disorganized house and realizing that no matter what I do, it won't say clean and organized for more than a couple of days, and I'll never, ever live in a place that looks like it's inhabited by a real grownup instead of a pack of drunken wolverines.
--looking at myself in the mirror and realizing that aging, overweight person is me.
--That feeling of restlessness that tells me I should be doing something meaningful or getting to my work/responsibilities, followed by overwhelming sleepiness and fogginess and complete cluelessness that kicks in when I try to tackle a difficult project or (lately) start writing a new story.