It actually a really important thing to learn to remember. It actually stems from the ancient law of greeting, which is part of the laws of courtesy and hospitality. To greet and start with the trivials, ie weather and so forth used to be a way in which you could assess the type of person you were meeting, ie friend or enemy etc. Little things like these laws are still very important these days.
I used to be very bad at this too, but I taught myself how to do it (and not analyse it too much). It's easier if you get in first. Say "G'day - how's it going?" - answer "Not too bad thanks and yourself" - answer "yeah, not too bad" or simply say back "Yeah, how's it going" They're short sentences with little direct meaning.
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"For he that does good, having the unlimited power to do evil deserves praise not only for the good which he performs, but for the evil which he forbears."
(W Scott)