I'm particularly likely to cry if I have a sore throat, or in pain some other way.
Sometimes people look a bit worried, or embarrassed, or contemptuous, or otherwise don't know how to react, so I just grab a tissue and say, "Oh, don't mind me, I cry at infomercials!" which usually raises a laugh (I did cry at an advert once, but I was heavily pregnant at the time).
I used to feel ashamed if I cried in front of someone, but now I don't worry about it too much - I don't yell at people or become aggressive, which is just as much of a loss of composure, and I've seen plenty of that in offices, too.
The book 'Radical Candour' talks about the difference between ruinous empathy and obnoxious aggression, advising a point somewhere in the middle: plain, clear and direct feedback that is delivered with kindness.
I'm disappointed that only 44% of senior executives believe crying from time to time isn't an issue: it really should be 100%.
I cried at my previous job was on my last day, when I got the final feedback of all the things my coworkers had been saying about me behind my back.
They'd been calling me "supportive" and "fun" and "enthusiastic."
I bawled my eyes out.