Both, I think on how I feel, I think about how other people feel. I read a lot of sub context from the specific words people choose to say and Freidan slips. For instance if someone says oh I really want shoes oh wait no I meant that jacket. Likely they want both, or perhaps they want shoes more than the jacket. I use this in my writing to ask myself what is the “normal” logical response to this situation, if this person feels this specific way. An example of this would be watching someone who suspected someone else in their life would likely kill someone else, laugh awkwardly threw an entire interview. It was an off putting chuckle, one that I have had experience with in the past. This particular chuckle gave me pause though because it sounded condescending. Why would a person have a nervous condescending laugh threw that kind of interview? Probably because they thought the two people involved, the one in prison and the one who was dead likely got what they deserved. For context Narcissist A is a substance abuse (committed the murder), Narcissist 2 was physically abusive (that person is now dead), the x giving the interview is Covert Narcissist 3. When writing something similar I would make sure that the covert narcissist who chuckled concededly would have constant thoughts of “Oh I hope they kill 2” and things like “I really hate this blank they’re always drunk. they were fat when I met them.” all the put downs really. and I would make sure he did it all with the nice guy smile. I use a lot of things I’ve gathered threw out my life, and also I listen to my favorite authors, such as George RR Martin where he talked about the difficulties of writing from a six year old’s perspective. How do six year old's think, hence why I often times ask children questions. Specifically mine mostly, but when I baby sit I also like to just listen and see how there doing. Based on those interactions I can deduce how a child would act vs a grown adult. So in those aspects I mainly talk about thinking.
When it comes to feeling, I often like to give emotions to the surroundings, to build a more layered context to the situation. For instance if I were writing a taxi scene with a couple who had just gotten over a very rough patch and were in a good place, I would focus on their thoughts, while also describing the feel of smooth leather. The cleanliness of the glass, pleasant conversation. How they feel changes the dialog, so there shouldn’t be a he snapped or she sighed, one showing aggressiveness while the other displays dismissal. For that the dialog responses would be she purred he agreed while his heart fluttered for the first time in years seeing the girl he married again, his eyes melted in the dark pools of her eyes, blah blah blah romance is boring and confusing having only had it once in my life a decade ago, I find it difficult to write. I hope that helps, though I could see how it would not. I believe in you!