Trace emotion causes. Magically acquire a gut-level realization that emotions are physical events in your brain and those events have physical causes (which may be other emotions or thoughts, since they're physical). I acquired this gut-level realization during the 2011 minicamp from User:Academian. Then, when you do manage to notice an emotion and have a moment, practice asking yourself what the proximate cause of that emotion was until it becomes a not-uncommon practice upon noticing a surprising emotion. To practice, you first need a way to notice emotions - either develop this, or ask someone else to cue you in whatever way the two of you choose, and precommit to ask yourself at their cue a) what your strongest emotion is currently, and b) what the largest components of that emotion's cause happen to be. I'm not sure what a good exercise for this might be, since it feels like you legitimately need an unanticipated emotion.