Can you find references about this? I googled but found nothing for that specific number. From what I can tell, emotions last on average in minutes (not seconds nor hours). But not sure how many minutes. Perhaps it varies for different emotions or different intensities. I read that when people feel an emotion last longer, like a couple of hours, it may not be even rumination or things you yourself doing but merely the same emotion repeating. Imagine someone having to face school bullies the next day. Or having a major surgery with a lower likelihood of success. Throughout the day they may have repeated pangs of fear and anxiety, almost like a kind of spasm, coming and freezing you and then leg go again. Certainly rumination or catastrophizing can make it all worse and make it last much longer or to encourage more frequent cycling of the emotion. But the emotion may cycle on its own anyways, either because of past experience or because the thing you are afraid of is actually quite life threatening. But I'm not questioning that we ourselves can do things to make situation worse and add a lot to our suffering.