Hi guys, I'll be going to Tanzania on some business stuff for a while - but before I go, I just thought I'd drop this absolute gem that came straight from my teacher. You cannot achieve yin yang gong (at least in mahamudra) without realizing the emptiness of BEING. Emptiness, like space is all around you, within and without. Unlike pure space, the emptiness of your being has the ability to be aware. To perceive and create countless realities. I asked my teacher to expand on the exact location and nature of yin and the correct method to combine it with yang within the lower dan tian in order to achieve the immortal body. His reply was I've been wondering, meditating and trying my best to really unlock the true power of yang energy that I feel inside of me. Using yin alone for telekinesis is nice - but it's NOTHING compared to when I've released yang on accident or during a moment of fright haha. I feel it in my muscles, skeleton, in my nervous fiber but it still remains trapped - and it will remain that way almost permanently unless I can finally truly REALIZE and EXPERIENCE the "void". I hope this helps anyone along the path, you can use this advice in any form of practice to gain a lot more insight into whatever you're doing. Best of luck !