I've been thinking about your query regarding stretching. Sarno said that physical discomfort and pain can be caused by the brain/mind causing mild oxygen deprivation (to attract your attention). If you believe that and you also believe that even just mild oxygen deprivation can cause pain varying from mild to severe in intensity, you then won't be reinforcing this as an "I'm broken/damaged" type of physical problem when you stretch to make yourself more comfortable. I think if it were me I would consider visualizing my muscles and tissues receiving oxygenated blood during and after exercising and while stretching. Dr James Alexander talks about TMS oxygen deprivation in his book https://www.amazon.co.uk/Hidden-Psy...ords=dr+james+alexander&qid=1589808250&sr=8-1 and he also has a visualization meditation that focusses on the sending oxygenated blood to the tissues. The latter is called 'Guided Imagery for Chronic Pain' and it can be download from his website here https://www.drjamesalexander-psychologist.com/apps/webstore/products/show/3402664 (Dr James Alexander). I think it's likely to be true to say that your muscles, ligaments and other tissues have probably 'atrophied' (for want of a better word) to a certain extent when you didn't exercise like you're doing now, but at some point soon, what with all the exercise you're regularly doing now, that won't be true to say, so my suggestion is to move your thoughts away from that and to instead visualize your muscles being bathed in oxygenated blood while you move and stretch.