It is not hard to experience the interrelationship of thought and emotion. For example, let's say we take a belief that I am not good enough. If you take that belief to be true, what does if feel like in the body. This is just a thought, a belief. But do you feel it in your head, or in the body? What emotions are co-arising as you take this belief to be true? Where in the body do you feel the emotion? Now let's take another belief, let's take the belief I am perfect just as I am. If you take this belief to be true, where do you feel it in your body? And what emotions co-arise with it? Where do you feel that emotion in your body?
You can try this also with memories, images, all kinds of cognitions. Can you have a cognition without a visceral feeling experience, or without emotion?
My own experience is that thought and emotion are always present together, and they always have a feeling right in the body somewhere, often in the chest region, that is, in the heart. Even though I have the cultural conditioning of thinking in the head, if I stop and examine my actual experience, the experience is mostly in the torso of the body, in the heart! Chances are high that I am not unique and this might be your experience too.
So it turns out that English is inadequate to express this, though we can turn it to reflect our true experience with some creativity. In the article I link to below, a Chinese man in a case study who is saying he could not rest, uses an expression that literally translates as I could not put my heart down. To draw attention to our true experiencing we might use expressions like body-mind or heart-mind.
If you have experiences of insomnia, perhaps next time you are laying awake you could amuse yourself by noting the experience in your body, rather than the churn of thoughts being in the head. Perhaps you could experience not being able to put your heart down on such a night. And see how it is an ever changing feeling-scape.
It comes back to somatic experiencing and yoga practice is about somatic experiencing, ever refining our ability to feel into even the subtlest experiences of the body. A slow and somatic yoga practice, whether you flow or hold postures, turning attention inward, reveals it all.
If you are interested, I found this academic article, Thinking Hearts, Feeling Brains:Metaphor, Culture, and the Self in Chinese Narratives of Depression that shows the cultural dimension of where we experience the seat of thought.
Image sourced from another nice article Wisdom is a Matter of Both Heart and Mind Neuroscience.com
