I think many in this discussion have mentioned these pieces. Here's my take.
Thinking psychologically means being curious and not trying necessarily to nail down a cause. Dr. Sarno said you can use your imagination when symptoms come up, asking the question "how might my Inner Child feel about this recent event, or what's happening now?" There is a lightness in this question.
An important part of this in my opinion is gently turning the mind from the physical causes (we've taken on as Gospel) to being open to a psychodynamic cause. This his huge in itself, and is subtle, and takes many many repetitions over the days. Repetition, with a gentle touch? And then the larger insights or feelings will come in their time. We're readying ourselves by opening the door to feelings, preparing a sense of safety about the deeper feelings.
Also, journaling about, or talking to another person can be very helpful, if you're willing to be free and feel, and be curious. This is different than ruminating and trying to fix.
For most people, insights and deeper feelings usually come with Inner Critic judgements. It is very helpful to learn to disengage with the Inner Critic to free awareness and feel feelings. Inner Critic activity can manifest as "overthinking" ---as inner dialogue, which distracts from deeper understanding, keeping us in a familiar orbit of mind vs a deeper felt sense. This inner dialogue can feel important, but is often repetitive thinking focused on problem-solving, fixing, justifying, explaining, inner arguing. The dialogue is a distraction, and it re-enforces identity with familiar sense of self. This familiar awareness of self is eventually penetrated by personal truths and insights such as have been shared in this discussion.
Using any of these techniques, we can tend to lean on them too heavily for symptom relief, which can add inner pressure, fueling symptoms. Best to take a very light hand in this, confident you'll know what you need to know.