You know how, when you first blow up a balloon, you stretch it out a couple of times first? This exercise stretches out your "energy body" (or whatever you call it). It's very good for when you feel tired or dejected, or as prep for other work.
Get comfortable and close your eyes. I do is sitting down, because I sometimes get a little dizzy when I do it, but you can stand up or lie down or whatever. Take a deep breath in making your spine very straight. Feel your whole body fill up like a balloon; your stomach should be very round. Breathe in and in and in until you're entirely full of air. You'll be amazed how much more air your lungs will hold than you usually put in them. Hold the air in for just a moment more than is comfortable, and then exhale. Exhale as much as you can, deflating your whole body like a balloon. Your shoulders relax and your head might dop a little. Keep your lungs empty for just a moment, and then repeat.
Once you've gotten a steady slow rhythm, imagine that not just your belly, but your entire body filling up, getting bigger and bigger with every inhale, and smaller and smaller with every exhale. The goal is to shrink to a single point (like a black hole) on exhale and become infinite (bigger than the universe) on inhale, but it’s ok to just get “very small” and “very big”.
Once you’ve gotten the hang of that (which takes quite a while), with each full-hold name yourself “Ein Sofit” (which is Hebrew for Infinity) and each time you hold-empty name yourself “Ein” (which means Nothingness). Or, you can just name yourself in English if you don’t want to use the Hebrew.
Whenever you’re done, start taking smaller, more usual breaths, and return slowly to your regular size by naming yourself with your regular name as you breathe.