A very interesting post. Excellent point about perspective and focus. Each of us can hone in on the same exact thing, but experience a myriad of different feelings and emotions.
Something I’ve found helpful is to keep a spreadsheet or list of my feelings/emotions when I experience them. For instance, if I feel restless or bored I write how my body feels, thoughts, and so on. I’ve used these experiences in my stories to give realistic depth of feelings and emotions to the characters.