teach me to express sympathy I have like two modes—"that sucks" (I'm stuck in traffic) & "I'm so sorry" (a building fell on my grandma)
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I do two things to kinda go in deeper (1) validating that whatever they're concerned about is a problem ("I know what you mean", "yeah that's terrible") or even longer sentences that just lay out the problem or confirm that the person they're bitching about is out of line so I throw some of that in. Another type of filler is the "keep your head up" style (hang in there, take care of yourself, stay strong etc.) and other sorts of buck-ups (praising them, valuing their contributions)
Sometimes it's so hard to get the tone in things right coz you don't want to be too familiar or too patronizing but besides that, tell me what phrases or things you use just for short term verbal or written communication of sympathy.