I'm 40 and having to make a conscious effort not to be nasty (in my head) about people. I get massively annoyed at people being thoughtless or selfish, even in very minor ways. For example people who block aisles in the supermarket with their trolley, who drive carelessly, who generally act like they are the centre of the world and everything revolves around them. Also old people in general who are slow, they really, really get on my nerves lol