Constructive Rest - Craig Thompson: Alexander Technique and Mindfulness

This seems to be the heart center of Shambhala

Constructive Rest
A Guide to this powerful self-help tool, inspired by the Alexander Technique, that can help anyone release harmful tension.
Constructive rest, sometimes known as "active rest", "semi-supine" or the "Alexander lying-down position" is an extremely effective self-help tool for Alexander Technique students, and for anyone else who wants a simple, practical way of releasing excess tension from their body.
The purpose of this page is to pull together in one place all the available information about constructive rest - articles, blogs, videos and audio resources. You'll find a variety of approaches to constructive rest here but there are three aspects that are pretty universal: 1. Lie on a firm surface; 2. Your knees should be elevated relative to your hips; and 3. There should (usually) be some support under your head. Most of the differences relate to what is most useful for you to think about (or not think about) while doing constructive rest. If you're new to the process, you might want to experiment with different suggestions.
https://www.youtube.com/watch?v=27Bg01JYRGo&feature=share
https://www.youtube.com/watch?v=_Oh-o0p_VKE
https://www.youtube.com/watchv=DjhEquSWAY0&list=PLo3ummXNQRRJQFmzrFccVG5s16KPITbfv
https://imogenragone.com/category/constructive-rest-2/
https://majoringinmusic.com/revitalizing-you-and-your-music/
http://alexandertechniquefoothills.com/blog/2009/05/15/constructive-rest/
http://www.expandingself.com/constructive_rest
http://www.posturematters.com.au/2011/12/resting-back-is-great-for-desk-bound.html