I haven't read "Biology of Belief" but I am familiar with the concept of epigenetics and the mind-body connection. How stress and other negative affective states induce inflammatory gene expression. Then there's also telomeres that degrade more quickly under stress.

So yeah, thoughts are incredibly powerful, both to the negative and positive, and not just to our external interactions but also to our internal interactions at the cellular level.

That's what gave me incentive early on to meditate and to pick it back up when I let it fall by the wayside.

More recently I began looking into the work of David Sinclair, NAD+, mitochondria and mitochondrial-encoded genes. I started a combination of Resveratrol and NMN about a month ago and also cold therapy, though not as extreme as Wim Hof.